ConverterHub

BTU to Kilowatt-hours Converter

Enter a value in btu to convert it to kilowatt-hours, joules.

How it is calculated

The tool multiplies the BTU amount by two constants: kWh = BTU × 0.00029307107 and J = BTU × 1055.05585. The input is an amount of energy in British thermal units. The kWh result is rounded to 4 decimals and the joule result to 2 decimals. Zero gives zero and negative numbers keep their sign, so the tool does not check for sensible values. The conversion runs one way only, from BTU to kWh and joules. To go back, divide kWh by 0.00029307107 (about 3,412 BTU per kWh). The tool converts energy, not power, so a rating in BTU per hour is not converted to kW.

Worked example

A catalogue lists the cooling effect of an air conditioner as 12,000 BTU and you want to compare it with an electricity bill. Step 1: kWh = 12,000 × 0.00029307107 = 3.51685 → 3.5169 kWh. Step 2: joules = 12,000 × 1055.05585 = 12,660,670.20 J. So 12,000 BTU of energy corresponds to about 3.5 kWh of electricity-equivalent energy.

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Common mistakes

  • Treating BTU/h (a rate of power) as BTU (an amount of energy). A 12,000 BTU/h air conditioner has a rated output of about 3.5 kW; the figure 3.5169 kWh is the energy of one hour of that rate, not a power rating.
  • Reading the answer as electricity cost without applying an efficiency. A gas furnace or heat pump delivers a different amount of heat per kWh of input than the conversion implies.
  • Confusing kWh with kW. kWh is energy, kW is power, and the tool outputs the former.
  • Typing a therm figure as plain BTU. A therm is 100,000 BTU, so entering 1 for 1 therm understates the energy by a factor of 100,000.

About this calculator

A British Thermal Unit (BTU) — the energy needed to raise one pound of water by one degree Fahrenheit — equals about 1,055.06 joules, while a kilowatt-hour (kWh) equals 3,600,000 joules, giving the conversion 1 BTU = 0.00029307 kWh (equivalently, 1 kWh ≈ 3,412 BTU).

HVAC engineers and appliance manufacturers rate air conditioners, furnaces, and water heaters in BTU or BTU/hr, while electric utilities bill in kWh — so converting between the two is a routine step when comparing the running cost of a gas-rated appliance against an electric one, or when sizing HVAC equipment against a home's expected energy usage.

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