BTU to kWh Calculator

How to use the BTU to kWh calculator

Enter an energy figure in BTU and this tool returns the same energy in kilowatt-hours — the unit your electricity meter counts. It is the reverse of the kwh-to-btu-calculator: instead of taking kilowatt-hours you already know and expressing them as British thermal units, you start from a BTU figure and convert it back to kWh.

One number in, one number out, and no dollars anywhere, because this is a straight unit conversion rather than a cost estimate. The input is pre-filled with 10,000 BTU so you can see the conversion before swapping in your own figure, and because the factor is a definition rather than a measurement, the result carries no uncertainty beyond the rounding on the display.

A BTU is a unit of energy — historically the heat needed to raise one pound of water by one degree Fahrenheit, and today fixed at exactly 1,055.05585262 joules — and a kilowatt-hour is also a unit of energy, so converting between them is just changing the scale, the way you would convert miles to kilometres.

Because both sides measure the same thing, the conversion factor is fixed and universal: it never depends on a price, a provider, a season, or where you live. That is what makes this tool clean. It answers how many kWh a given amount of energy is, and then it stops, leaving the money question to a tool that asks for your rate.

Which BTU figures convert cleanly, and which do not?

Use this tool when the BTU is genuinely an energy quantity: the heat content of a fuel, a heating load someone has quoted you in BTU, or any total BTU figure you want stated in kWh. The fuel quantities below are the comparisons this conversion was built for.

The formula, worked line by line

Both BTU and kilowatt-hours measure energy, so converting from one to the other is a single division by a fixed factor. One kilowatt-hour equals 3,412.14 BTU, so dividing a BTU figure by 3,412.14 gives the same energy in kWh. There is nothing to estimate and nothing personal to enter, because the relationship between the two units is settled by definition rather than by measurement.

The definition runs like this: a kilowatt-hour is one kilowatt held for one hour, which is 3,600,000 joules, and the international-table BTU used throughout energy statistics is fixed at 1,055.05585262 joules. Divide the first by the second and 3,412.14 falls out. The US Energy Information Administration publishes the same factor rounded to 3,412, so a small disagreement between an official conversion table and this tool is rounding rather than a different physical claim.

kWh = BTU ÷ 3412.14
BTU = kWh × 3412.14   (the reverse)
therms = BTU ÷ 100,000
electrical watts of an AC = cooling BTU per hour ÷ EER

Now the air conditioner caveat, worked through properly, because it is where this conversion is most often misread. The BTU on an air conditioner box is a cooling-output rate: heat moved per hour, not electricity consumed. A 10,000 BTU per hour unit does not use 2.93 kWh of electricity each hour.

Its electrical draw is the cooling rating divided by its efficiency in BTU per watt-hour, so at an illustrative EER of 12 the draw is 10,000 ÷ 12 = 833 watts, which is 0.83 kWh in an hour. That is 28 percent of the naive answer, and getting it wrong overstates the running cost by more than three times.

Where the conversion earns its keep

Where the conversion earns its keep is fuel comparison. Because a therm is exactly 100,000 BTU, one therm is 29.31 kWh of raw energy, and a gallon of propane at the 91,452 BTU heat content EIA publishes is 26.80 kWh.

Those figures are energy content only — they say nothing about how much of that energy reaches your rooms, which is a question of furnace AFUE or heat pump COP rather than of unit conversion. When you want that comparison with efficiency applied, the gas-vs-electric-heating-calculator is the tool that does it; when you want dollars from a genuine electrical figure, use the electricity-cost-calculator.

Questions people ask