Heat input calculator
Energy per unit weld length, from your welding parameters.
Choose the conditions to see the result.
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Method, scope & reference AWS D1.1 / D1.1M:2025
2025 base edition with July 28, 2026 errata. AMD1 not included.
How heat input is calculated
For conventional arc data, the calculator uses arc power per unit travel distance. Travel speed must describe the same weld segment as the current and voltage values.
For speed in mm/s, it uses volts × amps ÷ speed ÷ 1000. For speed in in/min, it first calculates kJ/in and converts by 25.4 mm per inch.
Waveform controlled methods use the equipment's measured total instantaneous energy per length, or average instantaneous power multiplied by arc time per length. Do not substitute average current multiplied by average voltage for waveform controlled instantaneous measurements. No efficiency factor is applied.
What this number does not tell you
Heat input is energy per unit length; it is not a prediction of weld temperature or a standalone pass/fail decision. Process-specific limitations, contract requirements, procedure variables and any additional controls must be reviewed separately.
Reference: AWS D1.1/D1.1M:2025 Clause 6.8.5 for the applicable heat input and waveform controlled measurement provisions. Confirm the exact clause path for the WPS route and governing contract.
Heat input questions
Which method should I select for pulsed or waveform controlled welding?
Use the equipment's waveform measurement basis where that is the applicable method: measured total instantaneous energy per weld length, or average instantaneous power and elapsed time per length. Use conventional current and voltage only when those are the relevant recorded values.
Does the result include an arc efficiency factor?
No. This calculator reports the calculation from the supplied electrical measurement and travel data without adding an efficiency factor.
Can I use this result to prove a WPS is qualified?
No. This tool calculates heat input only. WPS qualification and applicability depend on the governing code edition, the procedure route, recorded variables, materials, joint and project requirements.