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Watt-hours to Calories Converter

Convert Watt-hours (Wh) to Calories (cal) instantly, or use the conversion table below to look up common values.

1 Wh = 860.42065 cal

Watt-hours to Calories conversion table

Watt-hours (Wh)Calories (cal)
1860.42065
21,720.8413
32,581.26195
43,441.6826
54,302.10325
108,604.206501
2521,510.516252
5043,021.032505
10086,042.06501

How to convert Watt-hours to Calories

1 Wh equals 860.42065 cal. Use the converter above for any value, or read the table for common conversions.

cal = Wh × 860.4206500956022 · Wh = cal × 0.0011622222222222223

Multiply a watt-hours figure by 860.42065 to get calories, or divide it by 0.001162 to go the other way.

Worked examples

  • 1 Wh= 860.42065 cal
  • 5 Wh= 4,302.10325 cal
  • 10 Wh= 8,604.206501 cal
  • 100 Wh= 86,042.06501 cal
  • 500 Wh= 430,210.325048 cal

What these units are

Watt-hours (Wh). A watt-hour is the energy of one watt sustained for one hour — 3,600 joules. It is used for battery and power-bank capacity; a phone battery is typically 10 to 20 watt-hours.

Calories (cal). A calorie here is the small calorie of 4.184 joules — the energy needed to raise one gram of water by one degree Celsius. Food labels use the kilocalorie, which is 1,000 of these.

All factors are exact definitions, so only the display is rounded.

Converting Watt-hours to Calories in practice

Reading the result in calories

One thermochemical calorie is exactly 4.184 joules, a definition fixed by convention rather than by a water experiment. The food calorie on a nutrition label is a kilocalorie of 4,184 joules.

The small calorie appears in chemistry, physics and heat-capacity problems, where a substance's specific heat is expressed per gram per degree. Nutrition labels use the much larger food calorie instead.

Calories convert to joules by the exact factor 4.184, and kilocalories by 4,184, so no precision is lost in either direction. One kilocalorie is about 4.184 kilojoules, the same amount under another name.

Reading a nutrition label's calorie value as small calories understates the energy by a factor of one thousand. The figure printed there is always the kilocalorie, however it is capitalised or labelled.

The calorie shares its dimension with the kilocalorie, the joule and the kilojoule, and mixing them is the risk. A food label's figure is a kilocalorie, while mechanics and heat problems work in joules and kilojoules.

Checking a watt-hours to calories conversion

Energy units are defined against the joule, so every conversion in this dimension is a single exact multiplication by a published number rather than a chain of steps that could accumulate error.

The pair that needs care is the kilowatt-hour, because it looks like a power unit and is not. It is a watt sustained for an hour, which is why an electricity meter counts in kilowatt-hours while a generator is rated in kilowatts: one is an amount, the other is a rate, and only a duration links them.

To check an energy conversion, express both sides in joules or both in kilowatt-hours before comparing. The commonest mistake is treating a food calorie as a calorie when the label means a kilocalorie, which understates the figure a thousandfold.

Tanzania reference points

Real quantities, converted into the units on this page.

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