Watt Hours to Calories Converter

Watt Hours to Calories

Convert watt hours (Wh) to calories (cal). Both measure work and power, and the conversion comes up in nutrition, electricity, fitness work.

The Formula

`` calories = watt hours × 860.420650096 watt hours = calories × 0.00116222222222 `

One watt hour is 860.4207 calories, and one calory is 0.001162 watt hours.

Conversion Table

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

The Other Direction

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

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.

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.

A Sense of Scale

• A phone battery holds 12–20 Wh
• A laptop battery is 50–100 Wh
• A gram of sugar holds about 4,000 small calories

Precision

The factor 860.420650096 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 wattHourToCalorie = (value) => value * 860.420650096; ``

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	860	117,820	0.0489%
1	860.4	117,874.8	0.0024%
2	860.42	117,877.54	—
3	860.421	117,877.68	—
4	860.4207	117,877.64	—

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

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 calories is only good to three — writing more digits claims precision the measurement never had.