Watt Hours to Calories
Type a value in either box to convert between watt hours and calories. The factor is 860.421.
| Watt Hours | Calories |
|---|---|
| 1 Wh | 860.42065 cal |
| 2 Wh | 1720.8413 cal |
| 3 Wh | 2581.26195 cal |
| 5 Wh | 4302.10325 cal |
| 10 Wh | 8604.206501 cal |
| 25 Wh | 21510.516252 cal |
| 50 Wh | 43021.032505 cal |
| 100 Wh | 86042.06501 cal |
How to use
- Enter a value in the Watt Hours field.
- The Calories figure appears immediately — no button to press.
- Typing in the Calories field converts back to Watt Hours the same way.
- Use the reference table for the values that come up most often.
Watt Hours to Calories formula
Converting watt hours to calories is a single multiplication by 860.42065.
cal = Wh × 860.42065
Why this factor: the watt-hour and the calorie are both defined against the joule, so dividing one definition by the other gives 860.42065 directly. Both definitions are set out in full below.
To go the other way, divide by 860.42065 — or use the Calories to Watt Hours converter, which is the same calculation reversed.
Worked example
Start with 100 Wh. Multiply by 860.42065 to get 86042.06501 cal.
100 Wh × 860.42065 = 86042.06501 cal
The converter above does this for any value you type, in either direction.
What is a watt-hour?
A watt-hour is the energy delivered by one watt of power sustained for one hour.
Definition: Exactly 3,600 joules.
Where it is used: Battery capacity for laptops, e-bikes and power tools, and small-scale energy metering.
Worth knowing: Airline lithium-battery limits are set in watt-hours, which is why laptop and power-bank capacities are labelled in Wh.
What is a calorie?
A calorie is the energy needed to warm one gram of water by one degree Celsius.
Definition: The thermochemical calorie is defined as exactly 4.184 joules.
Where it is used: Chemistry and physics literature, and older engineering references.
Worth knowing: The 'calories' on a nutrition label are actually kilocalories — 1,000 of these. A 500-Calorie meal is 500 kcal, or about 2.1 million joules.
Watt Hours vs Calories
The watt-hour and the calorie belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many calories are in a watt-hour?
One watt-hour equals 860.42065 calories.
What is the formula to convert watt hours to calories?
Multiply the number of watt hours by 860.42065. To reverse it, divide by 860.42065 instead.
How do I convert calories back to watt hours?
Divide by 860.42065, which is the same as multiplying by 0.00116222222.
How many calories are in 10 watt hours?
10 Wh works out to 8604.206501 cal.
Is there anything to watch out for with watt hours?
Airline lithium-battery limits are set in watt-hours, which is why laptop and power-bank capacities are labelled in Wh.
How is the watt-hour defined?
Exactly 3,600 joules.