Energy Converter
Convert between energy units.
How to use the Energy Converter
- Type the number into Value. The page opens on Kilocalorie (kcal) to Kilowatt-hour (kWh).
- Choose your starting unit in the From list, then the target unit in the To list.
- Read the result below the fields. It updates on every keystroke, with nothing to submit.
Three units with the joule as the base
Every conversion passes through the joule. A kilocalorie is fixed at 4184 joules and a kilowatt-hour at 3,600,000, since 1000 watts for 3600 seconds is 3.6 million watt-seconds. One kilowatt-hour is therefore 860.42065 kilocalories.
| Unit | Joules |
|---|---|
| Joule (J) | 1 |
| Kilocalorie (kcal) | 4184 |
| Kilowatt-hour (kWh) | 3,600,000 |
One joule in kilowatt-hours rounds away to zero
Results are cut to six decimal places. One joule is about 0.00000028 kWh, below that limit, so it prints as 0. Run small amounts in the direction that gives a readable number: kilowatt-hours in and joules out, rather than the reverse.
Frequently asked questions
Are food calories the same as physics calories?
Food labels use the kilocalorie, written as Calorie with a capital C, which is 1,000 small calories. A 500 Calorie meal is 500 kcal.
Which unit do electricity bills use?
The kilowatt-hour, kWh, which is the energy used by a 1,000 watt appliance running for one hour.
How many kcal are in a kilowatt-hour?
About 860.4. A 1000-watt heater running an hour releases roughly the energy of 860 food Calories, though heat delivered and food energy taken in are different things.
Which calorie definition is used?
The thermochemical calorie, where 1 kcal is exactly 4184 joules. The international steam table calorie gives 4186.8 joules per kcal, a difference under 0.07 percent.
Where is the BTU option?
There is not one; the list holds joules, kilocalories and kilowatt-hours only. For BTU, convert to joules and divide by 1055.06, the international-table BTU.