Watt Hours to Kilocalories
Convert watt hours (Wh) to kilocalories (kcal). Both measure work and power, and the conversion comes up in nutrition, electricity, fitness work.
The Formula
``
kilocalories = watt hours × 0.860420650096
watt hours = kilocalories × 1.16222222222
`
One watt hour is 0.860421 kilocalories, and one kilocalory is 1.1622 watt hours.
Conversion Table
| Watt Hours | Kilocalories |
|---|---|
| 1 Wh | 0.860421 kcal |
| 2 Wh | 1.7208 kcal |
| 5 Wh | 4.3021 kcal |
| 10 Wh | 8.6042 kcal |
| 25 Wh | 21.5105 kcal |
| 50 Wh | 43.021 kcal |
| 100 Wh | 86.0421 kcal |
| 500 Wh | 430.2103 kcal |
| 1,000 Wh | 860.4207 kcal |
The Other Direction
| Kilocalories | Watt Hours |
|---|---|
| 1 kcal | 1.1622 Wh |
| 2 kcal | 2.3244 Wh |
| 5 kcal | 5.8111 Wh |
| 10 kcal | 11.6222 Wh |
| 25 kcal | 29.0556 Wh |
| 50 kcal | 58.1111 Wh |
| 100 kcal | 116.2222 Wh |
| 500 kcal | 581.1111 Wh |
| 1,000 kcal | 1,162.22 Wh |
What Each Unit Is
Watt Hours (Wh) — one watt sustained for one hour, or 3,600 joules. The practical electrical energy unit, following the adoption of the watt.
Kilocalories (kcal) — 1,000 small calories, or 4,184 joules — the "Calorie" on a nutrition label. Capitalised as Calorie to distinguish it, a convention almost nobody follows.
A Sense of Scale
A phone battery holds 12–20 Wh- A laptop battery is 50–100 Wh
- An apple is 95 kcal
- Daily intake is about 2,000 kcal
- A marathon burns roughly 2,600 kcal
Doing It in Your Head
Multiply by 6, then divide by 7. That is off by 0.38% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 8.6042 kcal 8.5714 kcal 86.0421 kcal 85.7143 kcal
Precision
The factor 0.860420650096 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
In Code
`javascript
const wattHourToKilocalorie = (value) => value * 0.860420650096;
``
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 Wh with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 Wh becomes | Error |
|---|---|---|---|
| 0 | 1 | 137 | 16.2222% |
| 1 | 0.9 | 123.3 | 4.6000% |
| 2 | 0.86 | 117.82 | 0.0489% |
| 3 | 0.86 | 117.82 | 0.0489% |
| 4 | 0.8604 | 117.875 | 0.0024% |
The right number of significant figures is set by your input, not by the converter. If you measured watt hours to three significant figures, the answer in kilocalories is only good to three — writing more digits claims precision the measurement never had.