kWh to Btu Converter
| kWh | Btu | The size |
|---|---|---|
| 1 | 3,412 | a kettle's full boil x6 |
| 10 | 34,120 | a 10 kW heater for one hour |
| 100 | 341,200 | an evening of electric heat |
| 1,000 | 3,412,000 | a month of family electricity |
Electricity is billed in kilowatt-hours, heating equipment is rated in Btu, and comparing the two is a daily task - heat pumps, space heaters, radiators and gas furnaces all publish their power in whichever unit their industry grew up with. The bridge is the one the EIA's conversion tables print: one kilowatt-hour equals 3,412 Btu. Type a number from any spec sheet or bill and the converter gives you the other side, plus megajoules and therms for good measure.
It helps to hold one anchor: a typical space heater drawing 1,500 watts for an hour delivers 1.5 kWh, which is about 5,118 Btu - roughly what a small gas burner puts out in 15 minutes at 20,000 Btu/hour. Every furnace-vs-heater comparison you will ever read is this one multiplication wearing different hats, and the honest versions all trace back to the same 3,412.
How to use
- Type kWh from an electric spec or bill to get Btu, or Btu/hour equipment ratings converted into the electric units your bill uses.
- The therm line answers the gas-bill question directly: about 29.31 kWh matches one therm, since both equal 100,000 Btu.
- For running-cost math, stay in kWh - your electric meter and rate are already in them - and convert the Btu side, never the reverse.
Frequently asked questions
How many Btu is one kilowatt-hour?
Exactly 3,412 Btu by the EIA's standard conversion - a slightly rounded print of the physical value 3,600 kilojoules divided by 1,055.05 joules per Btu. Working backwards, one Btu is about 0.000293 kWh, which is why gas equipment rated in tens of thousands of Btu per hour maps to only a few kilowatts: 34,120 Btu/hour is a 10 kW machine.
Is a Btu a unit of power or energy?
Energy - one Btu heats one pound of water by one degree Fahrenheit. The confusion comes from HVAC habit: furnaces are rated in Btu per hour, a power unit wearing an energy unit's clothes. A 40,000 Btu/hour furnace delivers about 11.7 kWh of heat every hour it runs, which is the number an electric comparison actually needs.
How does this help compare a heat pump with a gas furnace?
Convert everything to heat delivered, then divide by what you pay. A heat pump's spec lists electricity in kW - at a coefficient of performance near 3, a 3 kW heat pump delivers about 9 kW of heat, or roughly 30,700 Btu/hour. A gas furnace's 40,000 Btu/hour is about 11.7 kW of heat. Price both per delivered kWh and the winner falls out of your two rates, not the marketing.
What is a megajoule and where does it show up?
The SI energy unit - one kWh is exactly 3.6 megajoules (MJ) by definition, since a watt is a joule per second and an hour is 3,600 seconds. Gas appliances in Canada, Australia and New Zealand are rated in MJ/hour, so the MJ line is the bridge for imported specs that American and British Btu figures never quite meet.
Why do my own numbers not match my bill?
Bills add fixed charges, tiered rates and fuel adjustments on top of the raw unit price, and equipment ratings describe full output at test conditions. Converting units tells you how much energy moves; it cannot tell you what your utility charges for it. Compare units here, then price the converted figure against your actual rate schedule.