A watt-hour is 3,600 joules.
Watt-hours to Calories Converter — Wh to cal
Convert Watt-hour (Wh) to Calorie (cal) using the exact conversion factor (1 watt-hour = 860.4206501 calorie). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Watt-hours to Calories converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
A thermochemical calorie is 4.184 joules.
Result = input x 3600 / 4.184.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Watt-hours to Calories
Watt-hour and Calorie both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Watt-hour is typically associated with universal — standard consumer-electronics and battery energy unit worldwide, while Calorie is typically associated with nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie').
Formula
calories = watt-hours × 860.420650096
This factor comes from each unit's defined relationship to the category's base unit: 1 watt-hour equals 3600 base units, and 1 calorie equals 4.184 base units, so dividing one by the other gives the direct watt-hour-to-calorie factor of 860.420650096.
Simple example
1 Wh × 860.4206501 = 860.4206501 cal
1 watt-hour = 860.4206501 calories.
Real-world example
100 Wh × 860.4206501 = 86,042.06501 cal
100 watt-hours = 86,042.06501 calories.
Conversion table
| Watt-hour (Wh) | Calorie (cal) |
|---|---|
| 1 Wh | 860.4206501 cal |
| 10 Wh | 8,604.206501 cal |
| 100 Wh | 86,042.06501 cal |
| 500 Wh | 430,210.325 cal |
| 1,000 Wh | 860,420.6501 cal |
| 2,000 Wh | 1,720,841.3 cal |
Reverse conversion: Calorie to Watt-hour
860.4206501 cal × 0.001162222222 = 1 Wh
860.4206501 calories = 1 watt-hours.
watt-hours = calories × 0.00116222222222
For a page dedicated to this direction, see Calorie to Watt-hour.
Watt-hour vs. Calorie
| Aspect | Watt-hour | Calorie |
|---|---|---|
| Family | metric derived energy unit | Non-SI unit (limited use with SI) |
| Typical use | Phone, laptop, and power-bank battery capacity ratings | Food energy labeling (as kilocalories, often written 'Calories') |
| Where it's used | Universal — standard consumer-electronics and battery energy unit worldwide | Nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie') |
Understanding the Watt-hour
Watt-hour (Wh) measures energy. The energy delivered by one watt of power sustained for one hour — equal to 3,600 joules. It is classified as a metric derived energy unit.
Where it's used: Universal — standard consumer-electronics and battery energy unit worldwide
Wh vs. kWh. The same unit at different scales: 1,000 Wh equals 1 kWh. Wh suits small consumer-electronics batteries; kWh is used for household electricity billing and larger energy storage.
Uses of the Watt-hour today
- Phone, laptop, and power-bank battery capacity ratings
- Electric-vehicle battery capacity specifications
- Small-scale renewable energy (solar panel) output ratings
Understanding the Calorie
Calorie (cal) measures energy. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. It is classified as a Non-SI unit (limited use with SI).
Where it's used: Nutrition labeling in the US and several other countries still commonly uses the kilocalorie (as 'Calorie')
Calorie vs. Calorie (kilocalorie). Food labels' capitalized 'Calorie' is actually one kilocalorie (1,000 small calories) — a long-standing labeling convention that causes frequent confusion.
Uses of the Calorie today
- Food energy labeling (as kilocalories, often written 'Calories')
- Historical chemistry and thermodynamics contexts
History of the Calorie
The calorie was originally defined in the early 19th century as the heat needed to raise one gram of water by one degree Celsius, but different scientific traditions defined it at slightly different reference temperatures, producing several close but non-identical 'calorie' values historically (15 °C calorie, mean calorie, thermochemical calorie).
To resolve this ambiguity, the thermochemical calorie was fixed by convention at exactly 4.184 joules; the very similar International Table calorie is fixed at exactly 4.1868 joules. The nutritional 'Calorie' seen on food labels is actually a kilocalorie (1,000 calories).
Historical origin. Calorie was not the invention of a single named person; it developed through the process described above.
Watt-hour — sources
- BIPM SI Brochure — Watt-hour as a common energy unit derived from the coherent SI units watt and second (via the hour).
Calorie — sources
- NIST Special Publication 811 — Documents the thermochemical calorie's exact joule equivalence.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many calories are in 1 watt-hour?
1 watt-hour equals 860.4206501 calories, using the exact defined conversion factor rather than an estimate.
How do I convert watt-hour to calorie?
Multiply the watt-hour value by 860.4206501. The converter above does this instantly to whatever precision you set.
How do I convert calorie back to watt-hour?
Use the reverse factor: 1 calorie equals 0.0011622222 watt-hours. You can also use the swap control in the converter above to flip the direction instantly.
What is a watt-hour?
Watt-hour (Wh) measures energy. The energy delivered by one watt of power sustained for one hour — equal to 3,600 joules. It is classified as a metric derived energy unit.
What is a calorie?
Calorie (cal) measures energy. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. It is classified as a Non-SI unit (limited use with SI).
Is the watt-hour to calorie conversion exact?
Yes. The thermochemical calorie used in this converter is defined as exactly 4.184 joules. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between wh vs. kwh?
The same unit at different scales: 1,000 Wh equals 1 kWh. Wh suits small consumer-electronics batteries; kWh is used for household electricity billing and larger energy storage.
Where is the watt-hour still used today?
Universal — standard consumer-electronics and battery energy unit worldwide