kWh to BTU:
multiply by 3,412.14

How many BTU are in a kWh?

One kilowatt-hour is 3,412.141633 BTU (International Table). A kilowatt-hour is the energy used by a 1,000-watt appliance running for one hour, and it is the unit your electricity bill uses.

BTU is the older heat unit still printed on heaters, boilers and air conditioners. Converting kWh to BTU lets you compare what you pay for electricity with the heat output claimed on a label. The number is large because a BTU is a small quantity of energy: about 1.055 kJ against 3,600 kJ in a kWh.

The kWh to BTU formula

A mental shortcut: multiply the kWh by 3,400 and add a little. For 7.5 kWh that gives 25,500, close to the exact 25,591.

kWh to BTU conversion chart

Values are computed with the exact factor above. Large rows are shown in full so they can be copied into a spreadsheet.

Using kWh to BTU for heating and gas comparisons

Electric resistance heating turns one kWh into 3,412 BTU of heat, so a 3 kWh run of a fan heater delivers about 10,236 BTU. Gas appliances are often rated in BTU, so this factor is the bridge when you compare running costs.

Going the other way, a gas fire rated at 100,000 BTU of fuel energy is 100,000 × 0.0002930710702 = 29.31 kWh. A small 24,000 BTU burner is 7.03 kWh. These are energy amounts, not efficiency figures, so real heat delivered depends on the appliance.

A second worked example and a household check

A household sample makes the numbers concrete. If a home uses 12 kWh of electricity for heating in a day, that equals 12 × 3,412.141633 = 40,945.70 BTU of heat. A small 250 Wh appliance, which is 0.25 kWh, is 853.04 BTU.

Another example with time in it: a 2 kW heater that runs for 4 hours uses 2 × 4 = 8 kWh, so it releases 27,297.13 BTU. Multiply the power by the hours first, then convert the kWh total. A 25 kWh total would be 85,303.54 BTU.

Electric resistance heaters turn essentially all of their electricity into heat, so the conversion holds. Heat pumps can deliver more heat than the electricity they use, which means the BTU of heat can exceed the converted figure. Always check whether a BTU label describes the energy put in or the heat given out.

Comparing an electric heater with a BTU rating

A 2 kW electric heater running for 3 hours uses 6 kWh, which is 20,472.85 BTU of heat. That is a convenient way to compare it with a gas heater or boiler that is rated in BTU.

For larger totals the numbers grow quickly: 1,000 kWh is 3,412,141.63 BTU, about 3.41 million. A rate converts the same way, since 1 kW equals 3,412.14 BTU/h, so a 1.5 kW heater delivers about 5,118.21 BTU/h.

Common mistakes when converting kWh to BTU

• Forgetting the time unit. kW is power and kWh is energy, so a 2 kW heater uses 2 kWh per hour, not 2 kWh in total.
• Using 3,600 instead of 3,412. The figure 3,600 belongs to kJ per kWh, not BTU.
• Mixing BTU with BTU per hour on labels. Convert energy to energy and power to power.
• Assuming the answer is the heat you will feel. Real heat depends on efficiency, losses and the room.