Why are arc energy and effective heat different?

Effective heat includes process efficiency, so it represents the estimated energy transferred into the workpiece. Arc energy describes electrical energy per weld length before that adjustment.

Can I multiply displayed voltage by displayed current?

Use that product only when the electrical conditions support it. For pulsed or varying waveforms, use measured mean instantaneous power from suitable instrumentation.

Where should arc voltage be measured?

Measure near the arc using suitable instrumentation. Voltage at the power-source terminals can include cable losses and therefore differ from the voltage across the arc.

Which efficiency belongs in the input?

Use the factor required by your procedure or applicable reference. The cited reference lists 80% for gas metal arc welding, but this is a process estimate.

Welding & Fabrication calculator

Weld Heat Input Calculator

Calculate effective heat per weld inch from mean arc power and travel speed. Enter process efficiency and a procedure limit stated on the same heat basis.

What this calculator does

Calculate effective weld energy per inch and check it against your procedure limit.

Formula used

Arc energy (kJ/in) = mean arc power × 60 ÷ (1,000 × travel speed)
Effective heat = arc energy × thermal efficiency ÷ 100
Heat headroom = effective heat limit − effective heat

Inputs explained

Mean Arc Power: Measured time average of instantaneous arc voltage times current.
Weld Travel Speed: Welded distance divided by measured arc-on minutes.
Process Thermal Efficiency: Applicable process efficiency from the procedure or technical reference.
Effective Heat Limit: Procedure maximum on the same effective heat basis.

How to use the result

Best suited to procedure heat limit Check, travel speed sensitivity.
Pulsed power requires the time average of instantaneous voltage times current. Separate average voltage and current cannot determine arbitrary waveform power. This does not check minimum heat, interpass temperature or metallurgical acceptance.

Current U.S. benchmarks

The producer price index for steel mill products stands at 381.162 (BLS, Aug 2026), up 23.4% from a year earlier. Quotes priced off last quarter's material cost miss this move.
Industrial electricity averages 9.77 cents per kWh across the U.S. (EIA, Jul 2026), up 4.7% from a year earlier. Energy-intensive steps carry this directly into unit cost.
U.S. iron and steel import customs value ran $2.2B in Aug 2026 (Census International Trade). The U.S. ran a trade deficit of $0.6B in the category that month. This dollar total mixes price, quantity, product mix, origin, and timing; it does not measure physical import volume or prove a tariff or reshoring effect.
The U.S. has 53,790 fabricated metal products establishments employing about 1,441,471 workers (Census County Business Patterns, 2023).

Common questions

Why are arc energy and effective heat different? Effective heat includes process efficiency, so it represents the estimated energy transferred into the workpiece. Arc energy describes electrical energy per weld length before that adjustment.
Can I multiply displayed voltage by displayed current? Use that product only when the electrical conditions support it. For pulsed or varying waveforms, use measured mean instantaneous power from suitable instrumentation.
Where should arc voltage be measured? Measure near the arc using suitable instrumentation. Voltage at the power-source terminals can include cable losses and therefore differ from the voltage across the arc.
Which efficiency belongs in the input? Use the factor required by your procedure or applicable reference. The cited reference lists 80% for gas metal arc welding, but this is a process estimate.

Last reviewed 2026-10-06.