kWh to BTU, Joules and Therms Converter

Convert an amount of energy between kilowatt-hours, watt-hours, joules, megajoules, British thermal units and therms.

How it works

1 kWh = 3,600,000 J = 3.6 MJ exactly (NIST). 1 Btu (International Table) = 1,055.05585262 J exactly (NIST), so 1 kWh = 3,600,000 ÷ 1,055.05585262 = 3,412.14 Btu, which the U.S. EIA rounds to 3,412 Btu. 1 therm = 100,000 Btu and 1 MMBtu = 1,000,000 Btu, so 1 therm = 29.31 kWh.

Worked example: 1 kWh = 3,600,000 J ÷ 1,055.05585262 J per Btu = 3,412.14 Btu (EIA: 3,412). 1 therm = 100,000 Btu × 1,055.05585262 J ÷ 3,600,000 J per kWh = 29.31 kWh.

Assumptions

Btu means the International Table Btu used by NIST's exact factor.
Therm here means 100,000 Btu, the convention behind EIA's natural gas figures (103,700 Btu = 1.037 therms). NIST also lists a slightly different "therm (U.S.)" of 1.054 804 × 10⁸ J, about 0.02% smaller.
Energy units only. It does not account for appliance efficiency, such as how much useful heat a furnace or heat pump delivers from the energy it uses.
It does not convert natural gas volumes (cubic feet); the heat content of gas varies by location and over time (EIA).

Frequently asked questions

How many BTU are in a kWh?

3,412.14 Btu, from NIST's exact definitions (1 kWh = 3.6 MJ; 1 Btu = 1,055.05585262 J). The U.S. EIA's conversion calculator uses 1 kWh = 3,412 Btu.

How many kWh are in a therm?

With 1 therm = 100,000 Btu, one therm is about 29.31 kWh.

How many megajoules are in 1 kWh?

Exactly 3.6 MJ. NIST lists the kilowatt hour as 3.6 × 10⁶ joules (3,600,000 J).

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Sources

Formulas and reference values are from these sources. Page last reviewed 2026-10-19.