Welding Heat Input Calculator

The same heat input calculator built into Weld Audit Pro — arc energy and heat input to ISO/TR 18491 with a live weld-time stopwatch, thermal efficiency factors and WPS limit checks. Free for inspectors, welding engineers and QC teams.

Weld Time Stopwatch
0
.000
Stopwatch auto-fills weld time — HI, AE & TS calculate live
Parameters
Welding Process
Thermal Efficiency (η)
Amperage (A)
Voltage (V)
Weld Length
Weld Time (s)
WPS Heat Input Limits (optional)
Min kJ/mm
Max kJ/mm
Live Results
Travel Speed
—
mm/min
Heat Input
—
Arc Energy
—
kJ/mm
Heat input outside WPS limits
Formula (ISO/TR 18491)
Heat Input (Q) = (I × U × 60 × η) ÷ (v × 1000)  [kJ/mm]
Arc Energy (E) = (I × U × 60) ÷ (v × 1000)  [kJ/mm]
Travel Speed (v) = Weld Length ÷ Weld Time  [mm/min]

Doing this pass-by-pass on site?

Weld Audit Pro logs volts, amps and travel speed for every pass, applies the right efficiency factor automatically, and exports an audit-ready PDF — pWPS, WQT and weld audit forms included. Works offline. Free plan available.

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