How to Convert Calories to Kilowatt-hours (cal to kWh)
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 kilowatt-hours by hand, with examples and a quick-reference table.
The conversion
To convert calories to kilowatt-hours, multiply the value by 1.162222e-06. To go the other way, divide by the same number (or multiply by 860,420.6500956023). Because the factor is tiny, scientific notation keeps the numbers manageable.
Kilowatt-hours = calories × 1.162222e-06
Worked examples
- 3 cal = 3.486667e-6 kWh
- 12.5 cal = 1.452778e-5 kWh
- 75 cal = 8.716667e-5 kWh
Calories to Kilowatt-hours table
| Calories | Kilowatt-hours |
|---|---|
| 1 cal | 1.162222e-6 kWh |
| 2 cal | 2.324444e-6 kWh |
| 5 cal | 5.811111e-6 kWh |
| 10 cal | 1.162222e-5 kWh |
| 20 cal | 2.324444e-5 kWh |
| 25 cal | 2.905556e-5 kWh |
| 50 cal | 5.811111e-5 kWh |
| 100 cal | 0.000116 kWh |
| 250 cal | 0.000291 kWh |
| 500 cal | 0.000581 kWh |
| 1,000 cal | 0.001162 kWh |
Common questions
Is cal to kWh 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 Kilowatt-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.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Background
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the Calories to Kilowatt-hours Converter or browse all energy converters.
Run your own numbers: Calories to Kilowatt-hours Converter