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Energy
Calories to Watt-hours
Convert calories (cal) to watt-hours (Wh). Type a value below to see the result update instantly. Reference table and formula included.
Calculator
1 cal = 0.001162 Wh
Calories to Watt-hours Conversion Table
Common values, ready to copy:
| calories | watt-hours |
|---|---|
| 1 cal | 0.001162 Wh |
| 2 cal | 0.002324 Wh |
| 5 cal | 0.005811 Wh |
| 10 cal | 0.011622 Wh |
| 25 cal | 0.029056 Wh |
| 50 cal | 0.058111 Wh |
| 100 cal | 0.116222 Wh |
| 1,000 cal | 1.1622 Wh |
Formula
watt-hours = calories × 1.16222222e-3
Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.
About Calories and Watt-hours
Calories (cal): Originally defined as the energy to raise one gram of water by one degree Celsius; exactly 4.184 J in the modern definition (the thermochemical calorie). Common uses: Scientific work in chemistry, where the small calorie is the natural unit for heat-of-reaction measurements.
Watt-hours (Wh): The energy consumed by a 1-watt device in 1 hour; equals 3,600 joules. Common uses: Small battery capacities (laptop batteries are typically 40-100 Wh), and lighting energy use.
How the conversion works
Energy uses the SI joule. Food calories (kcal) are 1,000 small calories: 1 kcal = 4,184 J. 1 kWh = 3.6 MJ = 3,600,000 J. 1 BTU = 1,055.06 J.
The exact relationship is watt-hours = calories × 1.16222222e-3, which the calculator at the top of this page applies in both directions. Type into either field and the other updates immediately.
When this conversion matters
Converting between calories and watt-hours comes up wherever energy measurements move between systems — from one country's conventions to another's, from a scientific reference to a practical specification, or from one industry's working unit to another's. The calculator and reference table above cover the everyday range; for unusual values you can type any number into either field.