Heat input from volts, amps, and travel speed. AWS-style calculations use η = 1 — the same number a European sheet would call arc energy. EN 1011-1 style multiplies by a process factor: SAW 1.0, SMAW / GMAW / FCAW 0.8, GTAW 0.6. A starting figure for a traveler, not a WPS.
Use it when a welding procedure limits heat input — common on quenched-and-tempered steels, some stainless grades and code work — or when comparing two settings. Read volts and amps at the arc and time a measured length of weld for the travel speed.
The page gives arc energy and, with a process efficiency factor, heat input in kJ/in and kJ/mm, so you can check a pass against the limit in the procedure.
Electrical power is volts times amps. Time spent on one inch of weld is 60 / IPM seconds. Joules per inch are then V × A × 60 / IPM. Divide by 1,000 and you have kilojoules per inch. An efficiency factor η (k in EN 1011-1) scales that number for heat that never enters the plate — radiation, shielding gas, spatter, the flux blanket.
HI (kJ/in) = (V × A × 60 × η) / (travelIPM × 1000)
kJ/mm = kJ/in ÷ 25.4
AWS / ASME on this calculator: η = 1
EN 1011-1 on this calculator: SAW 1.0 · SMAW / GMAW / FCAW 0.8 · GTAW 0.6
Travel typed in millimetres per minute is converted to IPM (÷ 25.4) before the line above, so both unit systems share one formula. Millimetres per second, when a WPS prints them, are millimetres per minute ÷ 60 — convert that first; this calculator does not take mm/s.
AWS D1.1 and ASME Section IX typically record what EN would call arc energy and still name it heat input: no process factor. EN 1011-1 (and ISO 15614-1 practice) multiplies by k from a process table. For SAW the two systems match. For GTAW they differ by 40%. This page labels which one you asked for. It does not pick the code that owns your joint.
Pulsed and waveform-controlled GMAW may need instantaneous energy from the machine, not this steady V × A product. Weaving, stops, and restarts are your travel-speed problem, not a second formula. Timed a bead instead of reading a carriage? Use the welding travel speed calculator first, then bring the IPM here.
| Process | η (k) | Note |
|---|---|---|
| SAW — submerged arc | 1.0 | Flux blanket. Matches AWS η = 1. |
| SMAW — stick / MMA | 0.8 | Same k as MIG and flux-core on this table. |
| GMAW — MIG / MAG | 0.8 | Solid wire. Not a pulsed-energy method. |
| FCAW — flux-cored | 0.8 | Gas or self-shielded share 0.8 here. |
| GTAW — TIG | 0.6 | Heat lost to the tungsten and the gas. |
Those five numbers are the usual EN 1011-1 Table 1 set. This page is not selling a code edition. If your contract prints a different k, use that sheet, not this dropdown.
| Case | η | Heat input |
|---|---|---|
| 22 V · 180 A · 10 IPM (default, AWS) | 1.0 | 23.76 kJ/in |
| Same, EN SMAW / GMAW / FCAW | 0.8 | 19.008 kJ/in |
| Same, EN GTAW | 0.6 | 14.256 kJ/in |
| Same, EN SAW | 1.0 | 23.76 kJ/in |
| 28 V · 250 A · 10 IPM, AWS | 1.0 | 42.00 kJ/in |
| 22 V · 180 A · 254 mm/min, AWS | 1.0 | 23.76 kJ/in · 0.935 kJ/mm |
Shop check: 22 × 180 × 60 / (10 × 1000) = 23.76 kJ/in. Times 0.8 is 19.008; times 0.6 is 14.256. 254 mm/min is 10 IPM, so the last row is the same weld. Each of those six rows can be reproduced in the calculator above. The calculator rounds the big figure to two decimal kJ/in (19.01 and 14.26 on the EN rows) and three decimal kJ/mm.
Only when η is 1. AWS D1.1 and ASME IX usually skip the process factor, so the number is V × A × 60 / (IPM × 1000). EN 1011-1 multiplies by k. SAW stays at 1.0 both ways. Stick, MIG, and flux-core drop 20% on the EN calculation. TIG drops 40%. Compare a production weld to the same formula the PQR used, not to a number from the other system.
No. A WPS is a qualified document: process, filler, position, polarity, amperage, travel, preheat, and the code that owns the joint. This page multiplies the three numbers you type and, if you asked for EN, a table k. It does not qualify a welder, a machine, or a joint. If the work needs a WPS, get one. Starting number only.
Same energy per length, different unit. US shops and AWS sheets usually speak kilojoules per inch. EN / ISO sheets usually speak kilojoules per millimetre. Divide kJ/in by 25.4 to get kJ/mm. The calculator always prints both so a metric WPS and an imperial carriage speed can meet in the middle.
The speed along the joint — crater to crater — not the speed of the torch in the weave. A wide weave puts more heat into each inch of joint; this formula only sees how long you spent covering that inch. Time the length with a tape and a watch if the carriage readout includes oscillation you do not want.
Sometimes as a rough check, not as the qualified method. Waveform-controlled processes deliver energy in pulses. Many codes then want instantaneous energy or power from the machine, not average volts times average amps. If the WPS says “use the power-source energy readout,” this calculator is the wrong tool.
Use the voltage the procedure calls for. That is usually the arc or wire-feeder display, not the open-circuit number on the nameplate. Long leads drop volts. This page multiplies whatever V you type. It does not correct for a miscalibrated meter or a 50-foot whip.