Calories to Watt Hours
Convert calories (cal) to watt hours (Wh). Both measure work and power, and the conversion comes up in nutrition, electricity, fitness work.
The Formula
``
watt hours = calories × 0.00116222222222
calories = watt hours × 860.420650096
`
One calory is 0.001162 watt hours, and one watt hour is 860.4207 calories.
Conversion Table
| 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 |
| 500 cal | 0.581111 Wh |
| 1,000 cal | 1.1622 Wh |
The Other Direction
| Watt Hours | Calories |
|---|---|
| 1 Wh | 860.4207 cal |
| 2 Wh | 1,720.84 cal |
| 5 Wh | 4,302.1 cal |
| 10 Wh | 8,604.21 cal |
| 25 Wh | 21,510.52 cal |
| 50 Wh | 43,021.03 cal |
| 100 Wh | 86,042.07 cal |
| 500 Wh | 430,210.33 cal |
| 1,000 Wh | 860,420.65 cal |
What Each Unit Is
Calories (cal) — the energy to raise one gram of water by one degree Celsius, or 4.184 joules — the "small" calorie. A 19th-century thermal unit, displaced by the joule in physics but retained in nutrition.
Watt Hours (Wh) — one watt sustained for one hour, or 3,600 joules. The practical electrical energy unit, following the adoption of the watt.
A Sense of Scale
A gram of sugar holds about 4,000 small calories- A phone battery holds 12–20 Wh
- A laptop battery is 50–100 Wh
Precision
The factor 0.00116222222222 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
Watch Out For
- Food labels say "calorie" but mean kilocalorie — 1,000 of these. A 200-calorie snack is 200 kcal, or 837 kJ.
In Code
`javascript
const calorieToWattHour = (value) => value * 0.00116222222222;
``
Where This Conversion Comes Up
- Nutrition
- Electricity
- Fitness
- Heating
- Fuel
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 cal with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 cal becomes | Error |
|---|---|---|---|
| 0 | 0 | 0 | 100.0000% |
| 1 | 0 | 0 | 100.0000% |
| 2 | 0 | 0 | 100.0000% |
| 3 | 0.001 | 0.137 | 13.9579% |
| 4 | 0.0012 | 0.1644 | 3.2505% |
The right number of significant figures is set by your input, not by the converter. If you measured calories to three significant figures, the answer in watt hours is only good to three — writing more digits claims precision the measurement never had.