Welding Heat Input Calculator

Calculates the heat transfer in welding process.

Thermal Efficiency = 1

Heat Input Formulas

Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together.

Heat input is a relative measure of the energy transferred per unit length of weld. It is an important characteristic because, like preheat and interpasstemperature, it influences the coolingrate, which may affect the mechanical properties and metallurgical structure of the weld.To calculate the heat input for arc welding procedures, the following formula can be used:

Hi = A × V × 0.06s × T


Hi - heat input required in ampere volts min/mm

A - welding current A in amps

V - Arc voltage in volts

s - welding speed in mm/min

T - thermal efficiency (efficiency is dependent on the welding process used)

The thermal efficiency values for the different processes are given in the table below:

Welding processThermal efficiency
Tungsten inert gas (TIG)/gas tungsten arc (GTAW)0.6
Plasma arc (PAW)0.6
Metal inert/active gas (MIG/MAG) /gas metal arc (GMAW)0.8
Flux cored (FCAW)/Metal cored (MCAW)0.8
Manual metal arc (MMA)/shielded metal arc (SMAW)0.8
Submerged arc (SAW)1.0