A 250 kcal snack in kilojoules
250 × 4.184 = 1,046 kJ
Energy Converter
Convert joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU and electronvolts.
Result
1 kilocalorie (kcal) equals
4.184kJ
1 kcal = 4.184 kJ
1 kcal in every energy unit
| Unit | Value |
|---|---|
| Joule (J) | 4,184 |
| Kilojoule (kJ) | 4.184 |
| Calorie (cal) | 1,000 |
| Kilocalorie (kcal) | 1 |
| Watt-hour (Wh) | 1.1622222222 |
| Kilowatt-hour (kWh) | 0.0011622222 |
| British thermal unit (BTU) | 3.9656668314 |
| Electronvolt (eV) | 2.61145 × 1022 |
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How the Energy Converter works
Enter an amount of energy and choose the units — joules, calories, watt-hours, BTU or electronvolts. The result updates as you type, and the table below lists every unit.
All units are defined in joules. The calorie is the thermochemical calorie of exactly 4.184 J (the value used on food labels, where “Calories” mean kilocalories). One watt-hour is 3,600 J, because a watt is one joule per second.
Common conversions
Kilocalories to kilojoules
| Kilocalorie (kcal) | Kilojoule (kJ) |
|---|---|
| 50 kcal | 209.2 kJ |
| 100 kcal | 418.4 kJ |
| 200 kcal | 836.8 kJ |
| 250 kcal | 1,046 kJ |
| 500 kcal | 2,092 kJ |
| 1,000 kcal | 4,184 kJ |
| 2,000 kcal | 8,368 kJ |
Kilojoules to kilocalories
| Kilojoule (kJ) | Kilocalorie (kcal) |
|---|---|
| 100 kJ | 23.9 kcal |
| 500 kJ | 119.5 kcal |
| 1,000 kJ | 239.01 kcal |
| 2,000 kJ | 478.01 kcal |
| 8,700 kJ | 2,079.35 kcal |
Kilowatt-hours to british thermal units
| Kilowatt-hour (kWh) | British thermal unit (BTU) |
|---|---|
| 1 kWh | 3,412.14 BTU |
| 2 kWh | 6,824.28 BTU |
| 5 kWh | 17,060.71 BTU |
| 10 kWh | 34,121.42 BTU |
| 100 kWh | 341,214.16 BTU |
Kilowatt-hours to kilojoules
| Kilowatt-hour (kWh) | Kilojoule (kJ) |
|---|---|
| 0.1 kWh | 360 kJ |
| 0.5 kWh | 1,800 kJ |
| 1 kWh | 3,600 kJ |
| 5 kWh | 18,000 kJ |
| 10 kWh | 36,000 kJ |
Formula
result = value × ffrom ÷ fto
Where:
- ffrom
- Size of the starting unit in the base unit (1 kcal = 4,184 J, 1 kWh = 3,600,000 J)
- fto
- Size of the target unit in the same base unit
From power and time: energy (Wh) = power (W) × time (h).
Examples
One kilowatt-hour in BTU
3,600,000 ÷ 1,055.05585262 = 3,412.14 BTU
A 2,000 W heater running for 3 hours
2 kW × 3 h = 6 kWh = 21,600 kJ
Frequently asked questions
Is a food Calorie the same as a calorie?
No. A food Calorie (capital C) is a kilocalorie — 1,000 small calories, or 4.184 kJ. Food labels in many countries show both kcal and kJ.
What's the difference between kW and kWh?
kW is power (how fast energy is used); kWh is energy (how much was used). A 1 kW appliance running for one hour uses 1 kWh. Only energy units are converted here.
Which BTU does the converter use?
The International Table BTU, 1,055.05585262 J. Other BTU definitions differ from it by less than 0.5%.
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