Enter the welding current, arc voltage, and welding speed into the calculator to determine the welding heat input required.

Heat Input Formula

The following formula is used to calculate the heat input required for welding.

Hi = A * V * S / L
  • Where Hi is the heat input (Joules/inch)
  • A is the welding current (amps)
  • V is the arc voltage (volts)
  • s is the time (seconds)
  • L is the length (inch)

To calculate heat input required for welding, multiply the current by the voltage by the time, then divide by the length.

What is welding heat input?


A welding heat input is the amount of heat required to weld a piece of material at a certain current, voltage, and speed.

How to calculate heat input?

Example problem:

The following example problem outlines the steps and information required to calculate a required welding heat input.

First, determine the welding current. For this example, the welding current is 60 watts.

Next, determine the welding voltage. This welder uses a voltage of 120 volts.

Next, determine the total time of welding. In this example, the time is measured to be 100 seconds.

Next, determine the length of the weld. For this example, the length of the weld is 10 inches.

Finally, calculate the welding heat input using the formula above:

Hi = A * V * S / L

Hi = 60 * 120 * 100/10

Hi = 72,000 Joules/inch