Cabinet Heat Load Calculator

Work out cabinet heat load instantly with clear inputs, formula shown and shareable results.

About Cabinet Heat Load Calculator

Cabinet heat load is the sum of every component's dissipation plus external gain. The airflow needed for a given temperature rise is about 3.1 times the watts divided by the permitted rise in degrees, which comes from the specific heat and density of air.

Formula

Cabinet heat

airflow (m3/h) = 3.1 x watts / permitted temperature rise; 1 W = 3.412 BTU/h

Worked example

With the default values below, Cabinet Heat Load Calculator returns Total heat load of 575.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Drive and power electronics loss: 380 W
Control and PLC loss: 45 W
Transformer and PSU loss: 90 W
Solar or external gain: 60 W

Results

Total heat load: 575.0 W
Power electronics share: 66.1% %
Airflow for a 10 degree rise: 178.3 m³/h
Heat load: 1,962 BTU/h

Step by step

1Values used
2Cabinet heat
3Total heat load= 575.0 W
4Power electronics share= 66.1 %
5Airflow for a 10 degree rise= 178.3 m³/h
6Heat load= 1,962 BTU/h

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Where does the factor 3.1 come from?

From air's volumetric heat capacity, about 1.2 kJ per m3 per K, converted to cubic metres per hour per watt per degree.

Should solar gain be included?

Yes, and it can dominate. An enclosure in direct sun can absorb several hundred watts, which is why sun shields and light colours matter outdoors.