Free Arc Welding Heat Input Calculator

Calculate net heat input (kJ/in and kJ/mm) and arc energy according to ASME Section IX, AWS D1.1, and ISO/TR 17671 standards.

🔥 Arc Parameters & Process

Welding Process & Thermal Efficiency (η)

Welding Current (Amps)

Arc Voltage (Volts)

Travel Speed

Speed Units

Pass Length (inches)

Arc Time (seconds) Calculates travel speed

📊 Heat Input & Energy Values

Net Heat Input (Imperial) 0.0 kJ/in With process efficiency (η)

Net Heat Input (Metric) 0.00 kJ/mm 0 J/mm (EN 1011-1)

Arc Energy (Gross) 0.0 kJ/in Before thermal transfer factor

Arc Power (Kilowatts) 0.00 kW Instantaneous arc energy

Standard Reference Code: ASME IX QW-409.1 / AWS D1.1

Heat-Affected Zone (HAZ) Profile: Medium Heat Input (Optimal)

Calculated Travel Speed: 12.0 IPM (305 mm/min)

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Frequently Asked Questions

What is the formula for welding heat input in kJ/in?

Heat Input (kJ/in) = (Volts × Amps × 60 × Thermal Efficiency) / (Travel Speed in inches/min × 1,000).

What is the thermal efficiency factor for TIG and MIG welding?

Under ISO/TR 17671-1 and EN 1011-1, GMAW/MIG has a thermal efficiency factor of η = 0.80, SMAW/Stick is η = 0.80, FCAW is η = 0.80, and GTAW/TIG is η = 0.60.

How does travel speed affect heat input?

Heat input is inversely proportional to travel speed. Moving the welding torch twice as fast halves the heat input into the plate, producing a narrower heat-affected zone and faster cooling.

How do I convert heat input from kJ/in to kJ/mm?

Divide the kJ/inch value by 25.4 to obtain kJ/mm. For example, 38.1 kJ/in divided by 25.4 equals exactly 1.50 kJ/mm.