Technical resource
Costing a weld looks simple until you try it. How much consumable do you need, and what are the allowances. How long it will take. What influence on cost does changing from GMAW to MCAW have. Most estimates get built off the cost of a spool, on a job where the consumable makes up four per cent of the total cost.
Struggling to understand the ‘economics of welding’, and where your cost actually is. That’s what this is for. Put in the joint type, adjust the dimensions, select the welding process and consumable, and it gives you a guide on what welding it actually costs. Tweak the inputs to see the effect, and compare instantly against a different welding process, so you can make a technical decision with a figure behind it.
It helps you understand what drives the cost. From there you can change the process, improve production and take the cost out. That’s where optimising starts.
Estimate only An estimating aid, not a welding procedure. The pass schedule, travel speeds and arc energies follow from the deposition rate you enter and are not qualified parameters. Cost is dominated by the operating factor, which can be wrong by a factor of two. Check it against your own purchase records before you quote from it. Nothing here is checked against your steel, your consumable or your specification, and no warranty is given. This calculator sends your inputs to this site’s server to be calculated. They are not stored or logged. Full disclaimer and limitations are on the Method and data tab.
1. Pick the preparation
2. Dimensions and length
3. Process and production
Consumable and deposition rate
Gas, losses and pass model
Non-arc time, the twelve components
Used only when the time basis is set to explicit non-arc time. AWS notes this can be estimated accurately only for repetitive work. It is what justifies buying a positioner.
Rates and cost
Joint cross section
Drawn to scale from the dimensions entered.
Result
Derived pass schedule
| Run | Type | Side | Area mm² | kg/m | Travel mm/min | Arc energy kJ/mm | Heat input kJ/mm |
|---|---|---|---|---|---|---|---|
| Set the inputs above. | |||||||
Layers are built from the root up, split into beads by the maximum bead width and area you set. Travel speed follows from the deposition rate and the area of each run, so it is an implied speed for that deposition rate, not a qualified parameter. Heat input is arc energy times the thermal efficiency k.
What moves the answer
Each bar is the change in total cost when that input alone moves by the amount shown. If the top bar is operating factor or labour rate, refining the geometry will not change your quote.
The same joint, every process
Geometry, length, material and rates come from the Calculator tab. Deposition efficiency, deposition rate, current, voltage and gas flow are the defaults for each process, so this is a like for like comparison of the processes themselves, not of a particular consumable.
| Process | Eff. % | Rate kg/h | Op. factor | $ per kg | Filler kg/m | Flux kg/m | Labour h/m | Booked h | Gas m³ | Cost | Cost per m |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Set the inputs on the Calculator tab. | |||||||||||
Laid out the way AWS Table 8.17 lays out a cost standard: per metre of weld, showing filler, flux and labour hours side by side. Each row carries its own deposition efficiency, deposition rate, operating factor and indicative consumable price, because a comparison that holds the operating factor constant across manual and mechanised welding is not a comparison. Prices are placeholders. Labour, overhead, gas and power rates come from the Calculator tab. Set up, fixturing, positioning and equipment cost are not included, and AWS is explicit that published values are industry averages to be used as starting points, not as a bid.
Included angle against thickness
Narrowing the included angle cuts weld metal on thick sections and adds it on thin ones, because the wider root opening a narrow angle needs dominates below about 19 mm. Root openings follow Lincoln Table 12-8: 3.2 mm at 60 degrees, 6.4 at 45, 9.5 at 30, 12.7 at 20. Your material, cap height and rates are carried across from the Calculator tab.
| Thickness | 60° | 45° | 30° | 20° | Best | Saving against 60° |
|---|---|---|---|---|---|---|
| Set the inputs on the Calculator tab. | ||||||
kg of weld metal per metre, single V. The crossover is real: a calculator that recommends narrow preparations unconditionally is wrong on thin plate.
What a millimetre of fillet leg costs
| Leg | Nominal kg/m | Oversize | As welded kg/m | Arc hours per 100 m | Cost per 100 m | Against 6 mm |
|---|---|---|---|---|---|---|
| Set the inputs on the Calculator tab. | ||||||
Fillet volume goes with the square of the leg, and the overshoot a welder cannot avoid is a larger fraction on small welds. A 5 mm fillet as welded carries 61 per cent more metal than the drawing calls for, and needs the same metal as a 6 mm fillet. If the design allows either, specify 6 mm and get the throat for nothing.
Where the money actually goes
Every worked example in the Lincoln and AWS source material lands between 89 and 94 per cent labour and overhead. If your split looks different, check the operating factor first.
Project roll up
Every calculation you add lands here. Edit the quantity in place. Totals roll up to a purchase quantity, arc hours and cost for the whole project. Nothing is stored anywhere: the table lives in this browser tab only, so copy or download it before you close the page.
| Item | Joint | Process | Length m | Qty | Weld metal kg | Buy kg | Arc h | Total h | Cost | |
|---|---|---|---|---|---|---|---|---|---|---|
| Nothing added yet. | ||||||||||
| Project total | 0 | 0 | 0 | 0 | 0 | |||||
Disclaimer and terms of use
Read this before you quote from it Everything below applies to every number this page produces.
An estimating aid, not engineering advice. This estimates how much weld metal a joint holds and what it might cost to put there. It is not a welding procedure, not a joint design, and not a substitute for a WPS, a qualified procedure, or the judgement of a competent welding coordinator.
Nothing here is checked against your job. The tool does not know your steel grade, your consumable, your preheat, your weld category, your service conditions or your client’s specification. It does not check whether a preparation suits the code you work to, whether the joint can be welded in the position you have it, or whether the result is fit for purpose. Those are yours to determine.
The pass schedule, travel speeds and arc energies are derived, not qualified. They follow arithmetically from the deposition rate you enter. Do not transcribe them onto a WPS.
The cost output can be wrong by a factor of two. It is dominated by the operating factor, which varies more between two shops doing the same work than any other input in the model. The consumable prices, labour rates and gas prices are placeholders until you replace them with your own. Check the output against your own purchase records before you price work from it.
Standards. Where a standard is cited, the tool applies a single limit or tolerance from it. It does not reproduce the standard and is no substitute for one. Work from a current licensed copy of whichever standard applies to your job. Editions change and this page may not.
No warranty. This tool is provided as is, without warranty of any kind, express or implied, including as to accuracy, completeness or fitness for a particular purpose. To the extent permitted by law, Graham Fry accepts no liability for any loss, cost or damage arising from use of this tool or reliance on its output, including any error in the tool or in the data behind it. Nothing here excludes, restricts or modifies any right or remedy under the Australian Consumer Law that cannot lawfully be excluded.
Verify before you rely on it. If a number on this page would change a price you quote, a quantity you order or a decision you make, check it independently first.
Privacy. What you type is sent to this site’s server, calculated and sent straight back. It is not stored or logged, nobody sees it, and nothing is kept between visits.
The method, in the order the calculator applies it
Physical quantities first, rates last. That is the AWS Chapter 8 architecture, and it is what lets you change a labour rate without touching the engineering.
The cost set is Lincoln Table 12-5M, dimensionally verified. Labour and overhead are two separate hourly rates, as AWS Equations 8.18(4) and (5) treat them; set overhead to zero if you work with a single combined rate. Note that AWS’s own printed labour equation is inverted relative to its overhead equation and would understate labour by up to sixteen times at a 25 per cent operator factor, so the Lincoln set is used instead.
Deposition rate, four routes
Driving the deposition rate from wire feed speed rather than a lookup table is the single biggest accuracy gain available in a tool like this, and it is why consumable diameter matters here.
| Route | Formula | Use it when | Not valid for |
|---|---|---|---|
| Wire feed speed | Dh = d² × M × E / 2700 | You know the wire feed speed, from the machine or the WPS. The accurate route. | Solid core wire only. Not iron powder, not tubular. Cored wire is driven from metres per kilogram instead, because a flux core is less dense than steel. |
| Volts times amps | Mh = V × I / 2200 melted, deposited = Mh × E |
A quick estimate when nothing else is known. Deposition is roughly two thirds of the melting rate for stick. | Flux cored electrodes. Reads 0.9 to 1.8 kg/h high on submerged arc. |
| Measured | from the floor | Always, if you have it. Lay a tape along the electrode and time a minute, or read the wire feed speed off the machine. Shop measured values beat published procedure values. | — |
| Process default | table lookup by process, consumable diameter, position and weld metal | A first pass, before you have anything better. | Anything you are going to quote from without checking. |
Lincoln Table 12-3M and section 12.1-24, converted to metric and cross-checked against first principles: 1.2 mm wire at 10 000 mm/min and 98 per cent efficiency gives 5.23 kg/h by the formula and 5.22 kg/h from πd²/4 × density. Cored wire metres per kilogram were recomputed from AWS Table 8.13, whose printed metric column is out by a factor of 4.86 throughout.
The fillet oversize rule
A welder cannot hold a 5 mm fillet to the same proportional accuracy as a 20 mm one, so the overshoot is a much larger fraction on small welds. AWS Table 8.2 publishes the allowance banded by size. Decoding it against every row of the published table gives design area = nominal area × (1 + f)², which reproduces the table exactly.
| Leg size | Oversize f | Area multiplier | Nominal kg/m | As welded kg/m |
|---|---|---|---|---|
| 3 mm | 27% | 1.613 | 0.035 | 0.057 |
| 5 mm | 27% | 1.613 | 0.098 | 0.158 |
| 6 mm | 7% | 1.145 | 0.141 | 0.162 |
| 8 mm | 7% | 1.145 | 0.251 | 0.288 |
| 10 mm | 7% | 1.145 | 0.392 | 0.449 |
| 12 mm | 3% | 1.061 | 0.565 | 0.600 |
| 20 mm | 3% | 1.061 | 1.570 | 1.666 |
Two things fall out of this table and both are worth money. A 5 mm fillet as welded carries 61 per cent more weld metal than the drawing calls for, because volume goes with the square of the leg and the band is 27 per cent. And a 5 mm fillet needs essentially the same weld metal as a 6 mm one, 0.158 against 0.162 kg/m. If the design allows either, specify 6 mm and take the extra throat for nothing. Lincoln applies a flat 10 per cent instead of the bands; the banded rule is the better model and it is the one used here. One printed error to note: the 1/2 inch row of AWS Table 8.2 prints 1.7 in³/ft where the rule gives 1.6.
Cross-sectional area of each preparation
t thickness, b root gap, c root face, α included angle, β bevel angle, R root radius, z fillet leg, s prepared depth. On butt preparations β is measured from the plate normal, the same sense as α/2. On tee preparations β is measured from the flange face.
| Preparation | Deposited area, excluding cap | Status |
|---|---|---|
| Square butt, open root | b·t | verified |
| Single V | b·t + (t − c)²·tan(α/2) | verified |
| Single V on backing | b·t + t²·tan(α/2) | verified |
| Double V, split f | b·t + d₁²·tan(α/2) + d₂²·tan(α/2), d₁=f(t−c), d₂=(1−f)(t−c) | verified |
| Single bevel butt | b·t + (t − c)²·tanβ / 2 | verified |
| Single U | Closed form. Checked against numerical integration to twelve significant figures. | verified |
| Double U | Closed form. Checked against numerical integration to twelve significant figures. | verified |
| Single J butt | Closed form. Checked against numerical integration to twelve significant figures. | verified |
| Double J butt | Closed form. Checked against numerical integration to twelve significant figures. | verified |
| Fillet, equal leg | z² / 2 | verified |
| Fillet, unequal leg | z₁·z₂ / 2 | verified |
| Fillet with root gap | z²/2 + b·z | verified |
| Single bevel T, full penetration | b·t + (t − c)²·tanβ/2 + z²/2 | verified |
| Double bevel T | b·t + h²·tanβ + z², h = (t − c)/2 | verified |
| Single J T | Closed form. Checked against numerical integration to twelve significant figures. | verified |
| Double J T | Closed form. Checked against numerical integration to twelve significant figures. | verified |
| Partial penetration V | b·s + s²·tan(α/2) | derived |
| Partial penetration bevel T | b·s + s²·tanβ/2 + z²/2 | derived |
| Cap, any preparation | ⅔ · weld width · cap height | derived |
| Back gouge re-deposit | ⅔ · gouge width · gouge depth | derived |
How the root radius is set out
On a U or J preparation the radius is tangent to the root face and sweeps through (90 − β) to meet the straight flank, with the centre of the radius on the root face line extended. That gives a rounded bowl at the root roughly 2R wide, with the flank running off the tangent point. The common mistake, and one this calculator made in its first version, is to set the arc tangent to the side of the root land instead, so it sweeps only β. On a 25 mm single U at 10 degrees that hides the radius entirely and understates the weld metal by a factor of about three and a half. As a reference point, a 25 mm single U at a 10 degree flank, 6 mm radius, 3 mm root face, zero root gap and no cap returns 2.33 kg/m here. Quote the dimensions with the number before comparing it against any other tool: the root gap and the cap alone move it by 30 per cent.
What “checked” means here, precisely. Every closed form was compared against numerical integration of an independently written description of the same joint, and all eighteen agree to twelve significant figures. That proves the algebra, not the assumption behind it. The U and J formulae also collapse exactly to the single V and the single bevel when the radius is set to zero, which is a necessary condition, not a sufficient one. Where an external figure exists it is named. Nobody outside this page has verified anything, and the first version of this calculator shipped a U preparation that was wrong by a factor of three while passing both of those checks.
A convention trap worth knowing
Some published formulas give the single bevel area as (t − c)²·tanβ, twice what this tool returns. That is not necessarily an error: it is correct if their β is the included angle and wrong if it is the bevel angle. A single bevel has one flank, a V has two. Before concluding that two calculators disagree, check which angle each of them means. This one uses β as the bevel angle, measured from the plate thickness direction.
Deposition efficiency, percentage of purchased mass
Deposition efficiency is weld metal deposited divided by consumable purchased. It is not metal recovery to ISO 2401, which is measured against core wire only and can exceed 100 per cent for iron powder electrodes. It is also not operating factor, which is a labour term and has nothing to do with metal loss.
| Process | Published range | Default used | Source |
|---|---|---|---|
| SMAW rutile general purpose | 58 to 67 | 62 | Navy welding cost chapter 5; TestTalk |
| SMAW low hydrogen | 55 to 72 | 65 | Kobelco 55; The Fabricator 65; Navy 72 |
| SMAW iron powder | 65 to 72 | 68 | Navy welding cost chapter 5 |
| GMAW dip transfer, Ar mix | 90 to 93 | 93 | Lincoln C4.200 GMAW guide |
| GMAW dip transfer, CO₂ | 88 to 93 | 91 | Lincoln C4.200 |
| GMAW globular | 87 to 93 | 89 | Lincoln C4.200 |
| GMAW spray | 95 to 98 | 98 | Lincoln C4.200 |
| GMAW pulsed | 97 to 98 | 98 | Lincoln C4.200 |
| Metal cored | 92 to 96 | 95 | Hobart; Kobelco |
| Flux cored, gas shielded | 80 to 90 | 85 | Lincoln Outershield 71M measured 81 to 86 by diameter |
| Flux cored, self shielded | 73 to 83 | 78 | Lincoln Innershield NR-232 measured by diameter |
| GTAW, cut length rod | 90 to 100 | 92 | Off cut at 50 to 75 mm on a 1000 mm rod is 5 to 7.5 per cent. Sources quoting 100 are quoting melted mass |
| SAW, wire only | 99 to 100 | 99 | The Fabricator; Kobelco. Flux is a separate line |
Cross-check: TWI job knowledge 96 publishes multiplication factors of consumable purchased to weld metal deposited of MMA 1.5, TIG 1.1, MIG/MAG 1.05, SAW 1.02, FCAW 1.2 and MCAW 1.1, which correspond to 67, 91, 95, 98, 83 and 91 per cent. The spread on SMAW across published sources is 55 to 72 per cent, which is a 20 per cent swing on the quantity you order. Use your own consumable data sheet where you have one.
Stub loss, and why there is no stub input
A fixed stub is a bigger fraction of a short electrode, so SMAW efficiency runs with electrode length. AWS Table 8.11 is the only source that publishes it that way.
| Electrode length | AWS published range | Used here, E4918 |
|---|---|---|
| 300 mm | — | 63% |
| 350 mm, common Australian stock | 55 to 65% | 65% |
| 450 mm | 60 to 70% | 70% |
| 700 mm | 65 to 75% | 75% |
Each electrode type keeps its own efficiency at 350 mm (rutile 62, low hydrogen 65, iron powder 68 per cent) and the electrode length moves it by the AWS Table 8.11 step. The column shows the low hydrogen figures.
Three different numbers get called efficiency
Deposition efficiency is deposited divided by melted: spatter, slag and fume. Overall efficiency is deposited divided by purchased, which adds the stub. Lincoln’s worked example: buy 50 kg, 10 kg left on the reel, so 40 kg used; 5 kg of stubs, so 35 kg melted; 25 kg deposited. Deposition efficiency 71.4 per cent, overall efficiency 62.5 per cent. AWS quotes the overall figure, and it already contains the stub loss. This calculator carries one overall efficiency for that reason, and has no separate stub input. Take an efficiency from an AWS table and then deduct stubs on top of it and you have double counted them by 15 to 20 per cent. The first version of this page did exactly that.
Operating factor, arc time as a share of attendance
| Situation | Range | Source |
|---|---|---|
| Production, jigged and repetitive | 0.35 to 0.50 | CIS Suite |
| Structural fabrication in the shop | 0.25 to 0.45 | CIS Suite; TestTalk |
| One off and custom fabrication | 0.20 to 0.35 | TestTalk |
| Site welding | 0.15 to 0.30 | CIS Suite |
| Repair work | 0.15 to 0.25 | TestTalk |
| Mechanised and SAW | 0.80 to 0.95 | TWI job knowledge 96 |
| All manual welding, industry average | 0.20 | The Fabricator, 12 minutes of arc per hour |
TWI job knowledge 96 gives arc time as a share of working time: MMA 15 to 30 per cent, TIG 25 to 40, MIG/MAG 30 to 45, mechanised 80 to 90, SAW 80 to 95, and states that these exclude set up and assembly. Labour and overhead dominate every worked example in the source material: 89 per cent in Lincoln Problem 3, 94 per cent in the NAVEDTRA example, and the US Navy welding cost chapter puts power under 1 per cent. That is why getting the operating factor right matters more than any other input.
Operating factor, arc time as a share of clock time
Lincoln’s caution is the one to remember: an error of 0.10 at the low end of the range is a 33 per cent error in the answer, while the same error at 0.80 is 8 per cent. Operating factor accuracy matters far more in manual welding than in mechanised. Verify it by measuring your own consumable usage per week against what the calculator says you should have used.
| Welding method, AWS Table 8.15 | Band | Process default, AWS Table 8.20 | Used here |
|---|---|---|---|
| Manual | 5 to 30% | SMAW and GTAW | 25% |
| Semiautomatic | 10 to 60% | GMAW, FCAW, MCAW | 35% |
| Mechanised | 40 to 90% | SAW | 50% |
| Automated | 50 to 100% | Robotic | set your own |
AWS categorises by method rather than by process, which is the more honest cut: a MIG gun in a bad position with heavy repositioning is closer to 10 per cent than to the 35 per cent a process table suggests. TWI’s process ranges, for cross-reference: MMA 15 to 30, TIG 25 to 40, MAG 30 to 45, FCAW 25 to 45, MCAW 30 to 45, mechanised TIG and MAG 80 to 90, mechanised FCAW 70 to 85, SAW 80 to 95. The Welder put the real industry average at about 20 per cent in 2023, which is twelve minutes of arc in an hour.
Operating factor is not a productivity score
Lincoln’s worked example: a job runs 16 minutes of arc and 16 minutes of downtime, a 50 per cent operating factor, 15 units a day. Double the arc speed and it becomes 8 minutes of arc and 16 of downtime: the operating factor falls to 33 per cent and output rises to 20 units. A lower operating factor with a higher arc speed is a win. Never compare operating factors across dissimilar conditions, and never rank options by operating factor alone.
Shielding gas, scaled with current
A flat flow rate ignores the procedure. AWS scales it: gas consumption for GMAW and FCAW is roughly 10 to 15 ft³ per 100 A per hour, which converts to 4.7 to 7.1 L/min per 100 A.
| Current | Low, 4.7 L/min per 100 A | High, 7.1 L/min per 100 A |
|---|---|---|
| 150 A | 7.1 | 10.6 |
| 200 A | 9.4 | 14.2 |
| 250 A | 11.8 | 17.7 |
| 300 A | 14.2 | 21.2 |
| 400 A | 18.9 | 28.3 |
TWI’s flat 12 to 15 L/min sits inside that band at 250 to 300 A. Above about 25 L/min turbulence starts aspirating air, so a high figure is not automatically a safe one. Gas is billed by time, not by weld metal, so a higher deposition rate cuts the gas bill proportionally: AWS Table 8.14 deposits the same 136 kg with 30 m³ by GMAW and 20 m³ by FCAW, purely because FCAW gets it done in 20 hours instead of 30.
Guard rails built into this tool
| Rule | Why |
|---|---|
| Multipass joint speed is 1/S = 1/S₁ + 1/S₂ + … | Averaging arc speeds and dividing by the pass count is wrong. Lincoln’s example: 406 and 254 mm/min average to 165 mm/min the naive way, 156 mm/min correctly. The error grows as the speeds diverge. |
| The wire feed speed formula is refused for cored wire | d²M/2700 assumes a solid cross section. A tubular electrode gives more metres per kilogram than solid wire of the same diameter, so the tool switches to measured length per mass. |
| The volts times amps rule is flagged for flux cored | Lincoln states it is not satisfactory for them, and reads 0.9 to 1.8 kg/h high on submerged arc. |
| One overall efficiency, no separate stub deduction | Mixing the two conventions double counts stub loss by 15 to 20 per cent on SMAW. |
| Deposition rates are not compared across processes to infer cost | Lincoln: “it is a mistake to equate deposition rate to overall welding costs when considering the various processes, because of the wide differences in the accompanying mechanical operations.” |
| Each process in the comparison carries its own operating factor | Costing SAW at a manual shop factor overstates it by about 80 per cent. |
| Fields belonging to other joints cannot reach the calculation | A hidden input changing the answer is the worst failure an estimating tool can have. |
| A process that cannot weld the joint in that position or weld metal is not costed | SAW overhead, iron powder electrodes out of position or flux cored wire on titanium would otherwise rank as the cheapest option. The Calculator flags it and Compare shows it as not usable. |
Published errors found while building this
Every one of these was found by cross-checking rather than by reading, and each would silently corrupt a calculator built by transcribing tables.
| Source | Error | Effect if imported |
|---|---|---|
| AWS Table 8.5 | mm³/mm column is ten times low from the 10 mm row down | Metric weld metal understated tenfold on single V butts |
| AWS Table 8.13 | m/kg column divided by 2.2046 instead of multiplied, every row out by 4.86 times | Cored wire consumable length wrong by nearly five times |
| AWS Table 8.2 | the 1/2 inch row prints 1.7 in³/ft where the rule gives 1.6 | Minor, one row |
| AWS Table 8.14 | one cell reads “1 m³/h (18.9 L/min)”. 18.9 L/min is 1.134 m³/h | Gas out by 13 per cent depending which half of the cell you use |
| AWS Table 8.17, 12.7 mm row | SAW labour prints 0.230 h/m. At the process data AWS states for that table, 6.8 kg/h and a 65 per cent operator factor, it is 0.337 h/m. The SMAW column of the same row reconciles to three decimal places, and the 6.4 mm row reconciles on both columns | SAW labour understated by a third on that row |
| AWS Equation 8.18(4) | operator factor inverted relative to the structurally identical overhead equation | Labour understated up to sixteen times at a 25 per cent operator factor |
| AWS Equation 8.18(11) | prints a plus where a division is required | Nonsense result |
| AWS Equation 8.18(13) | flux ratio 1.5, contradicting the chapter text and Table 8.17 which both use 1.0 | Flux overstated 50 per cent |
| AWS Equation 8.18(2) | no power source efficiency term, despite Table 8.1 listing it as a cost variable | Power understated 15 to 100 per cent |
| Lincoln Table 12-8 | the 12.7 mm 45° cell and the 203 mm 60° cell do not match their own metric columns | Minor |
The general rule that falls out of it: never read a metric column out of either source without checking it against the imperial original. Both books were written in US customary units and several of the metric columns are rounded labels rather than real conversions.
Weld metal density
Density sources disagree by 0.8 per cent on carbon steel: AWS Table 8.10 gives 7.8, AWS Table 8.18 gives 7.83, Lincoln 7.833 and TWI 7.86. This tool uses 7.85 g/cm³, the midpoint, and states it. The spread is immaterial next to the efficiency and geometry uncertainty.
| Weld metal | g/cm³ | Basis |
|---|---|---|
| Carbon and low alloy steel | 7.85 | verified Kobelco, universal in estimating |
| Austenitic stainless 308 and 308L | 8.02 | verified Kobelco |
| Austenitic stainless 316 and 316L | 8.03 | verified Kobelco |
| Ferritic 18Cr and martensitic 13Cr | 7.75 | verified Kobelco |
| Duplex 2209 | 7.80 | interpolated between ferritic and austenitic by phase balance |
| Nickel alloy, generic | 8.51 | verified Kobelco |
| ERNiCrMo-3, alloy 625 | 8.44 | verified Special Metals bulletin |
| ERNiFeCr-1, alloy 825 | 8.14 | verified Special Metals data |
| Aluminium 4043 and 4047 | 2.69 | verified Washington Alloy line sheet |
| Aluminium 5356 and 5183 | 2.64 | derived alloy data, no manufacturer sheet sighted |
| Titanium, ERTi-2 | 4.51 | verified Kobelco |
| Copper, ERCu | 8.90 | estimate standard value, no welding consumable source sighted |
Excess weld metal and convexity, the ISO 5817:2023 limits
Here b is the width of the weld, not the root gap. The calculator warns when the cap height you entered exceeds the limit for the quality level selected.
| Imperfection | Level D | Level C | Level B |
|---|---|---|---|
| 1.9 excess weld metal, butt weld | h ≤ 0.25b + 1, max 10 mm | h ≤ 0.15b + 1, max 7 mm | h ≤ 0.1b + 1, max 5 mm |
| 1.10 excessive convexity, fillet weld | h ≤ 0.25b + 1, max 5 mm | h ≤ 0.15b + 1, max 4 mm | h ≤ 0.1b + 1, max 3 mm |
Welding to the level B cap limit on a 20 mm 60 degree V costs about 21 per cent more weld metal than the theoretical groove. A realistic as welded cap of 1 to 2 mm costs 5 to 10 per cent, which is where the trade factor of 1.05 to 1.15 comes from. That factor is trade practice, not a code requirement. For work to AS/NZS 1554.1 the governing acceptance limits are in its Table 6.2.2 for categories SP and GP, not ISO 5817. Set the cap height from the standard you are working to.
Default dimensions, and what to change
Back gouge is on by default for double sided full penetration joints and for single sided full penetration tees. Changing the preparation keeps the thickness, and keeps the root gap, root face and cap when both preparations have them, so the change in weld metal is like for like. Reset defaults loads every default again. Imperial equivalents are shown in brackets after the metric values. Every preparation opens on the dimensions a fabricator would reach for first: 60 degrees included on a V, 45 degrees on a bevel or a J, 10 degrees per flank on a U, with a root gap and root face to match. They are deliberately plain. The joint you are actually welding comes off the drawing and the procedure, so type your own dimensions over the top and the diagram and the numbers follow.
What is worth changing before you trust a figure, in the order it moves the answer: the operating factor, the deposition rate, the consumable price, then the geometry. Geometry is the part this tool gets exactly right and the part that matters least to the total.
The angle, and where it is measured from
The angle field is the included angle of the preparation. On a single or double V that is the full included angle between the two prepared faces. On a bevel or a J the opposing member is square, so the included angle is the single flank angle. On a U it is the angle between the two flanks, so a 20 degree U is 10 degrees per flank, and the tool halves it for you and says so. Read that one the wrong way and a U groove comes out at roughly double the metal. This is the single most common way to get a U or J wrong on paper.
The datum is the prepared member’s through-thickness direction. On a butt joint that reads as an angle off the plate normal. The same prepared edge stood on a flange becomes the T joint, so on a tee the angle reads off the flange face and the depth of preparation is measured across the web thickness. One cut, one angle, whichever joint it ends up in.
The root radius on a U or J is drawn with the centre of the radius on the root face line extended, so the arc is tangent to the root face and sweeps out to meet the flank. That is the construction this tool uses, and a numerical reconstruction of the profile agrees with the closed form area to better than a tenth of a per cent.
Fit up tolerance, Table 5.2.2
The consumable range is swept across the allowable joint tolerances rather than a guessed band. The tolerances are not symmetric, so the sweep is run low to high on each dimension independently.
| Dimension | Tolerance |
|---|---|
| Root face, root not gouged | ±1.5 mm |
| Root gap without backing, root not gouged | ±1.5 mm |
| Root gap with backing | +6, −1.5 mm |
| Root radius, root not gouged | +3, −0 mm |
| Angle of preparation | +10°, −5° |
AS/NZS 1554.1 Table 5.2.2. Where the root is gouged back to sound metal these tolerances may be disregarded. Note that a joint fitted at the top of every tolerance is still a compliant joint, so the upper figure in the range is what you should be buying to, not the nominal.
Reinforcement, Table 6.2.2
The cap height limit can now come from AS/NZS 1554.1 rather than ISO 5817. SP category limits the reinforcement on each side of a butt weld to 3 mm up to 12 mm thick, 5 mm from 12 to 25 mm and 6 mm above 25 mm. On a fillet it is 2 mm up to 12 mm leg, 3 mm from 12 to 25 mm and 4 mm above. GP does not limit reinforcement at all; the tool keeps the SP figure as a working cap so the pass build up stays sensible, and says so.
Fillet welds with a root gap, Clause 5.2.3
Where the separation between the parts is 1.5 mm or greater, the fillet leg shall be increased by the amount of the separation, or the fabricator has to demonstrate the design throat was obtained. Most estimates miss this entirely. On an 8 mm fillet both sides with a 3 mm gap it is the difference between 0.440 and 0.734 kg/m, 67 per cent more wire, before any oversize allowance. The tool applies it by default on the fillet with root gap preparation and lets you turn it off.
Working ranges for the eighteen preparations
These are the ranges a fabricator works inside, not limits. Anything outside them will still calculate, and the diagram will show you why it is a bad idea.
| Preparation | Usual thickness | Angle | Root gap | Root face | Radius |
|---|---|---|---|---|---|
| Square butt, open or closed root | up to about 6 mm | – | 0 to half the thickness | – | – |
| Single V, one or both sides | 5 to 40 mm | 60° included | 0 to 4 mm | 0 to 4 mm | – |
| Single V on backing | 5 mm up | 45 to 60° included | 6 to 12 mm | 0 | – |
| Double V, back gouged | 20 mm up | 60° included each side | 0 to 4 mm | 0 to 6 mm | – |
| Single and double bevel, butt or T | 6 mm up | 45°, 60° for submerged arc | 0 to 4 mm | 0 to 6 mm | – |
| Single and double U | 25 mm up | 8 to 12° per flank | 0 to 3 mm | 1 to 6 mm | 6 to 10 mm |
| Single and double J, butt or T | 25 mm up | 30 to 45° | 0 to 4 mm | 0 to 3 mm | 6 to 12 mm |
| Steep flanked V, narrow gap | 16 mm up | 5 to 20° per flank | 5 to 15 mm | – | – |
| Fillet, equal or unequal leg | any | – | 0 to 3 mm | – | – |
A steep flanked preparation and a conventional 60 degree V are different joint families for different processes, so do not interpolate between them. The wide root opening on the steep flanked row is the defining feature of that preparation, not a misprint: it is the only access the electrode has. A U below about 25 mm thick can use more weld metal than a plain V, which is why the tool compares the two for you and tells you when the U is the wrong choice.
What is checked, what is derived, what is a modelling choice
| Item | Status |
|---|---|
| Every cross-sectional area formula | checked against numerical integration of an independently written profile, all eighteen agreeing to twelve significant figures, and against the TWI worked example. A self consistency check, not external verification |
| Fillet oversize bands | checked decoded from AWS Table 8.2 and reproduces every row of it |
| Deposition rate from wire feed speed | checked Lincoln Table 12-3M, agrees with first principles to 0.2 per cent |
| Deposition efficiency by electrode length | checked AWS Table 8.11 |
| Operating factor bands and defaults | checked AWS Tables 8.15 and 8.20, cross-referenced against TWI |
| Cost formula set | checked Lincoln Table 12-5M, reproduces Lincoln Problems 1, 3 and 4 to the printed cent |
| Weld metal densities | checked AWS Table 8.10 alloy groups, carbon steel reconciled across four sources |
| ISO 5817 cap limits | checked 2023 edition, clauses 1.9 and 1.10. Applies to steel, nickel and titanium only: aluminium is ISO 10042 and the check is suppressed for it |
| Parabolic cap area | modelling choice Lincoln Problem 3 uses the parabola, TWI uses a triangle. The parabola gives 33 per cent more cap metal for the same width and height. Declared so nobody cross-checking against TWI thinks it is a bug |
| Pass count and the pass schedule | modelling choice layers from the root up, split by maximum bead width and area. No published source gives a pass count rule. It is a defensible estimate, not a WPS |
| Travel speed and arc energy per run | derived from the deposition rate and the run area. Consistent within the model. Not welding parameters |
| Position factor on deposition rate, bead size and current | estimate no source derates deposition rate or operator factor for position. Named as a gap by the source material |
| Repair allowance | estimate the metal allowance is twice the repair rate, the time allowance is the repair rate times the multiplier. A repair is mostly labour. No source quantifies it |
| Consumable, gas, power, labour and overhead rates | placeholder indicative Australian figures. Put your own in before you quote |
| Repair rates | checked TWI industry survey: 2.0 per cent mild steel all products, 3.0 per cent piping, 3.4 per cent nickel alloy, peaks to 25 per cent |
| Joint design and compliance | not implemented the setups are estimating starting points, not joint designs. Nothing here checks consumable grade, steel grade, preheat, weld category, or whether the joint suits the code you work to |
What this does not do
This is an estimating tool. It does not qualify a preparation, a procedure or a welder, it does not set welding parameters, and it does not replace the standard that applies to your work. The pass schedule, travel speeds and heat inputs are model outputs consistent with the deposition rate you entered, not qualified parameters from a WPS or a PQR. Weld metal quantity is geometry and is reliable to within the accuracy of your fit up. Consumable quantity carries the efficiency uncertainty in the table above, which is up to 20 per cent on SMAW. Cost carries the operating factor uncertainty, which can be a factor of two. Add 5 to 10 per cent for tack welds, run on and run off tabs, and wastage. Check the answer against your own purchase records before you rely on it for a quotation.
Sources
TWI job knowledge 96, welding costs · TWI repair rate survey · Lincoln Electric C4.200 GMAW welding guide · Kobelco, calculation of welding consumables consumption · The Fabricator, deposition rate and efficiency · ESAB submerged arc welding technical handbook · Hobart Brothers, groove weld geometry · ISO 5817:2023 · ISO/TR 18491 and EN 1011-1 for arc energy and thermal efficiency · Special Metals alloy bulletins · Washington Alloy aluminium filler metal line sheet
Terms of use
The calculator, its method, its data and the software behind it are the work of Graham Fry and are protected by copyright. You may use the calculator, and the results it gives you, in the ordinary course of your own work, including in estimates and quotations for your own clients.
Without written permission, you must not access the calculator by automated means, including scripts, bots, scrapers or crawlers. You must not submit inputs in bulk or at a rate beyond ordinary manual use. You must not copy, reproduce or reverse engineer its method, data or outputs in order to build, train or supply another calculator, dataset or software product, and you must not use its outputs to train or evaluate an artificial intelligence or machine learning model.
Access may be limited or blocked where use appears automated or excessive. All rights not expressly granted are reserved. Nothing in these terms limits any right you have under the Australian Consumer Law.
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Graham Fry, International Welding Engineer. Welding, fabrication and pressure equipment consulting: procedure and qualification work, independent technical review, and expert opinion.
This tool is free, and nothing you enter into it is stored. It is an estimating aid provided without warranty: see the disclaimer at the top of this tab before relying on any number it produces.