Calories to BTU Converter
Convert Calories (cal) to BTU (BTU) instantly, or use the conversion table below to look up common values.
Calories to BTU conversion table
| Calories (cal) | BTU (BTU) |
|---|---|
| 1 | 0.003966 |
| 2 | 0.007931 |
| 3 | 0.011897 |
| 4 | 0.015863 |
| 5 | 0.019828 |
| 10 | 0.039657 |
| 25 | 0.099142 |
| 50 | 0.198283 |
| 100 | 0.396567 |
How to convert Calories to BTU
1 cal equals 0.003966 BTU. Use the converter above for any value, or read the table for common conversions.
BTU = cal × 0.003965666831390919 · cal = BTU × 252.1644007217973Multiply a calories figure by 0.003966 to get btu, or divide it by 252.164401 to go the other way.
Worked examples
- 1 cal= 0.003966 BTU
- 5 cal= 0.019828 BTU
- 10 cal= 0.039657 BTU
- 100 cal= 0.396567 BTU
- 500 cal= 1.982833 BTU
What these units are
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.
BTU (BTU). A BTU (British thermal unit) is 1,055.05585262 joules — the energy needed to heat one pound of water by one degree Fahrenheit. It is used for heating and cooling capacity.
All factors are exact definitions, so only the display is rounded.
Converting Calories to BTU in practice
Working 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 calories to btu 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.
One unit of electricity on a Tanzanian prepaid meter
1 kWh = 860,420.650096 cal = 3,412.141633 BTU
The average domestic rate was about 229.59 TZS per kWh as of December 2025, including taxes and supply. That is an average across domestic customers, not the marginal rate on a bill.
Source: GlobalPetrolPrices — Tanzania electricity prices (compiled from EWURA/TANESCO tariffs) · verified 2026-09-14
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