Kilowatts (kW) and British thermal units (Btu) are both measurements of energy. Btu, sometimes called heat units, are often associated with domestic heating systems running on gas, oil or steam, while kilowatts and kilowatt-hours are more commonly associated with electricity. Before it is possible to calculate Btu from kilowatts, the kilowatts must be converted into kilowatt-hours (kWh). A straightforward conversion formula then determines the kilowatt-hour equivalent in Btu. A calculator is required.
Express the kilowatts as kilowatt-hours. A kilowatt-hour is 1kW of power delivered for a period of one hour. For example, an appliance using 1kW of power for one hour uses 1 kWh, and an appliance using 2kW for 30 minutes has also used 1 kWh of power.
Multiply the value in kilowatt-hours by 3,412, the number of Btu equivalent to 1 kWh. The result is the value expressed in Btu. For example, 100 kWh is equivalent to 341,200 Btu because 100 x 3,412 = 341,200.
Add either "British thermal units," or Btu, as a suffix to the result of the conversion. This shows the units used. For example, write 341,200 either as 341,200 British thermal units, or as 341,200 Btu.
Find, and use, an online conversion applet to perform the conversion for you. The more precise conversion value is 3412.141633 = 1 kWh.
Double-check the results to eliminate errors. This is particularly important when the results are used for practical purposes such as designing heating systems.