Welding Heat Input Calculator

Calculate heat input, travel speed, or amperage

Formula

HI (kJ/in) = (V × A × 60 × η) / (TS × 1000). η = process efficiency. 1 kJ/in = 25.4 J/mm.

Heat input is the energy deposited per unit length of weld. It's controlled by voltage, amperage, travel speed, and process efficiency. Critical for weld quality and code compliance.

How to Calculate Manually

1
Select what to calculate
2
Enter known welding parameters
3
Select welding process for efficiency factor
4
Calculator shows the unknown parameter

Reference Table

Process	Efficiency	Typical HI Range (kJ/in)
SMAW (Stick)	0.80	30-70
GMAW (MIG)	0.90	20-50
FCAW-G	0.90	30-60
FCAW-S	0.85	35-65
GTAW (TIG)	0.70	10-30
SAW	1.00	50-100

Welding Heat Input Calculator: kJ/in, Travel Speed, Amperage

Heat input is one of the most critical variables in welding. It determines the thermal cycle experienced by the base metal and weld metal, directly affecting microstructure, mechanical properties (especially toughness), distortion, and residual stresses. Most welding codes (AWS D1.1, ASME Section IX, API 1104) require heat input to be controlled within specified limits...

Frequently Asked Questions

What is heat input? Heat Input (HI) = (Voltage × Amperage × 60) / (Travel Speed × 1000) in kJ/in. It affects microstructure, mechanical properties, and distortion.: Heat Input (HI) = (Voltage × Amperage × 60) / (Travel Speed × 1000) in kJ/in. It affects microstructure, mechanical properties, and distortion.
What are typical heat input ranges? SMAW: 30-70 kJ/in. GMAW: 20-50 kJ/in. FCAW: 30-60 kJ/in. SAW: 50-100 kJ/in. GTAW: 10-30 kJ/in.: SMAW: 30-70 kJ/in. GMAW: 20-50 kJ/in. FCAW: 30-60 kJ/in. SAW: 50-100 kJ/in. GTAW: 10-30 kJ/in.
Why control heat input? High HI → coarse grains, lower toughness, more distortion. Low HI → lack of fusion, high hardness. Codes (AWS D1.1, ASME IX) often specify min/max HI.: High HI → coarse grains, lower toughness, more distortion. Low HI → lack of fusion, high hardness. Codes (AWS D1.1, ASME IX) often specify min/max HI.

Calculator

Formula

Formula

How to Calculate Manually

Reference Table

Welding Heat Input Calculator: kJ/in, Travel Speed, Amperage

Frequently Asked Questions

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