How to Convert Calories to Watt-hours (cal to Wh)
Energy conversions link food labels in kJ and kcal, SP Group bills in kWh and air-conditioner capacity in BTU. This guide shows how to convert calories into watt-hours by hand, with examples and a quick-reference table.
The conversion
To convert calories to watt-hours, multiply the value by 0.0011622222. To go the other way, divide by the same number (or multiply by 860.4206500956). For a quick estimate, multiply by about 0.0012.
Watt-hours = calories × 0.0011622222
Worked examples
- 3 cal = 0.003487 Wh
- 12.5 cal = 0.014528 Wh
- 75 cal = 0.087167 Wh
Calories to Watt-hours table
| Calories | Watt-hours |
|---|---|
| 1 cal | 0.001162 Wh |
| 2 cal | 0.002324 Wh |
| 5 cal | 0.005811 Wh |
| 10 cal | 0.011622 Wh |
| 20 cal | 0.023244 Wh |
| 25 cal | 0.029056 Wh |
| 50 cal | 0.058111 Wh |
| 100 cal | 0.116222 Wh |
| 250 cal | 0.290556 Wh |
| 500 cal | 0.581111 Wh |
| 1,000 cal | 1.1622 Wh |
Common questions
Is cal to Wh exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Watt-hours to Calories converter.
Mistakes to avoid
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Background
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
For any value, use the Calories to Watt-hours Converter or browse all energy converters.
Run your own numbers: Calories to Watt-hours Converter