1,000 cal to BTU — 1,000 calories in British thermal units
Exact 1,000 ÷ 252.164401 = 3.965667
1,000 calories in other units
| Joules | 4,184 | J |
|---|---|---|
| Kilojoules | 4.184 | kJ |
| Megajoules | 0.004184 | MJ |
| Watt-hours | 1.162222 | Wh |
| Kilowatt-hours | 0.001162222222 | kWh |
| Kilocalorie | 1 | kcal |
| British thermal units | 3.965667 | BTU |
| Therms | 0.000039656668 | thm |
| Foot-pounds | 3,085.96 | ft·lbf |
| Electronvolts | 26,114,473,967,543,832,805,376 | eV |
cal to BTU at a glance
| Calories | British thermal units |
|---|---|
| 1 cal | 0.003965666831 BTU |
| 2 cal | 0.007931333663 BTU |
| 3 cal | 0.011897 BTU |
| 5 cal | 0.01982833 BTU |
| 10 cal | 0.03965667 BTU |
| 20 cal | 0.07931334 BTU |
| 25 cal | 0.09914167 BTU |
| 50 cal | 0.19828334 BTU |
| 100 cal | 0.39656668 BTU |
| 250 cal | 0.99141671 BTU |
| 500 cal | 1.982833 BTU |
| 1,000 cal | 3.965667 BTU |
How to convert calories to British thermal units
Multiply by 0.003965666831 — one calorie is 0.003965666831 British thermal units. That factor is exact: it comes from the definition of the units rather than from a measurement, so it will not change and does not need rounding.
Working 1,000 ÷ 252.164401 = 3.965667
In words: about four British thermal units.
What these units are
The calorie and the British thermal unit are covered in the energy unit guide, along with every other unit on this page.
Questions
How many British thermal units are in a calorie?
One calorie is 0.003965666831 British thermal units. This figure is exact — it comes from the definition of the unit, not a measurement.
What is 1,000 calories in British thermal units?
1,000 calories is 3.965667 British thermal units. The working is 1,000 ÷ 252.164401 = 3.965667.
Is a food Calorie the same as a calorie?
No — it is a thousand of them. The Calorie on a nutrition label is a kilocalorie, written with a capital C in principle and almost never in practice. A 250 Calorie chocolate bar holds 250,000 physics calories, or about 1,046 kilojoules, which is why European labels quote kJ alongside.
What does a kilowatt-hour actually represent?
One kilowatt drawn for one hour — a 1,000 W heater running for sixty minutes, or a 100 W bulb for ten hours. It is the unit your electricity bill is priced in, and it equals exactly 3.6 million joules.
How much energy is one BTU?
Roughly the heat needed to raise one pound of water by one degree Fahrenheit — about 1,055 joules, or the energy in a single kitchen match. Air conditioners are rated in BTU per hour, where a 12,000 BTU/h unit is one "ton" of cooling and draws around 3.5 kW of heat.
Why is the electronvolt so small?
Because it is sized for single particles: it is the energy one electron picks up crossing a one-volt potential difference. At about 1.6 × 10⁻¹⁹ joules it would be absurd for anything larger, which is precisely why particle physics uses it instead of dragging around twenty leading zeros.