Energy Converter: kWh, Joules, Calories, BTU, Therms
Convert joules, kJ, kWh, calories, kilocalories, BTU and therms, with the factor shown.
Inputs
| Unit | 2,000 Kilocalorie is |
|---|---|
| Joule | 8,368,000 |
| Kilojoule | 8,368 |
| Calorie | 2,000,000 |
| Kilocalorie | 2,000 |
| Watt-hour | 2,324.444444 |
| Kilowatt-hour | 2.324444 |
| BTU | 7,931.332555 |
| Megajoule | 8.368 |
| Therm (US) | 0.079332 |
- Factor
- 1 Kilocalorie = 4.184 Kilojoule
- Working
- 2,000 × 4.184 = 8,368
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What each Energy input means
- Value
- The amount of energy to convert: food energy, an electricity reading, a gas bill, a heater rating over time.
- From
- Joules and their multiples are SI; kilocalories are food energy; kWh and Wh are electricity; BTU and therms are US heating and gas units.
- To
- The unit you want. Every unit is tied to the joule: a kWh is exactly 3.6 MJ and a thermochemical calorie exactly 4.184 J.
Energy conversion formula
result = value × (joules in one 'from' unit ÷ joules in one 'to' unit) · 1 kWh = 3,600,000 J
Every energy unit converts through the joule. A kilowatt-hour is a kilowatt for an hour — 1,000 W × 3,600 s = 3.6 million joules — and is how electricity is billed. Food energy is in kilocalories (the 'Calorie' on a label) at 4.184 kJ each. Heating uses the British thermal unit, 1,055.056 J, and US gas bills the therm, about 100,000 BTU. The page shows the factor, the working and your amount in all of these.
Energy conversion worked example
2,000 kcal × 4.184 = 8,368 kJ — the same day's food energy in the units on a European label. In electrical terms it is 2.32 kWh. And the question that brought someone here: 300 kJ of electricity is 300,000 ÷ 3,600,000 = 0.083 kWh.
More Energy examples
A 250 kcal snack in kilojoules, the unit on Australian and EU labels: 250 × 4.184 = 1,046 kJ.
A day's 30 kWh of electricity in heating units: 30 × 3,412.14 = 102,364.234695 BTU, about one therm.
One US therm on a gas bill is 29.300111 kWh, so gas at 1.50 a therm costs about 0.051 a kWh of heat, before boiler losses.
Where the Energy converter can give the wrong answer
- Calorie with a capital C on food labels means kilocalorie. A small calorie is 1/1,000 of that.
- Kilowatt-hours are energy; kilowatts are power. A 2 kW heater for 3 hours uses 6 kWh.
- Several BTU definitions exist; the International Table BTU used here (1,055.056 J) is the usual one, and the others differ by under 0.1%.
- The calorie here is the thermochemical one (4.184 J), which food labelling uses; the International Table calorie is 4.1868 J.
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Energy conversion reference table
| Amount | Kilojoules | Kilowatt-hours | Kilocalories | BTU |
|---|---|---|---|---|
| 1 kcal (food Calorie) | 4.18 | 0.0012 | 1 | 3.97 |
| 2,000 kcal | 8,368 | 2.3244 | 2,000 | 7,931.33 |
| 1 kWh | 3,600 | 1 | 860.42 | 3,412.14 |
| 1 MJ | 1,000 | 0.2778 | 239.01 | 947.82 |
| 1 BTU | 1.06 | 0.0003 | 0.25 | 1 |
| 1 therm (US) | 105,480.4 | 29.3001 | 25,210.42 | 99,976.12 |
Energy conversion FAQ
- A food Calorie (kilocalorie) is 4.184 kJ. 2,000 kcal is 8,368 kJ.
- 3,412: 3,600,000 J ÷ 1,055.056 J.
- A US therm is 105.48 MJ — about 100,000 BTU, or 29.3 kWh. Natural gas is billed in therms in the US.
- 0.083 kWh. A kilowatt-hour is 3,600 kJ, so 300 kJ is 300 ÷ 3,600 of one — about what a 1 kW kettle uses in 5 minutes.
- Yes. A capital-C Calorie on a food label is 1 kcal, 4.184 kJ. A 2,000-Calorie day is 8,368 kJ.
- About 29.3 kWh. Gas bills in therms can be compared with electricity in kWh by multiplying therms by 29.3.
- 3,600: a watt is a joule per second, and an hour is 3,600 seconds. A kilowatt-hour is 3.6 million joules.
- 0.239: divide kilojoules by 4.184. A 1,000 kJ snack is 239 kcal.
- 1.5 kWh — power times time. That is 5,118 BTU of heat.
- The heat needed to warm one pound of water by one degree Fahrenheit, about 1,055 joules. Furnaces and air conditioners are rated in BTU per hour.
- 860.4 kcal: 3,600,000 J ÷ 4,184.
- 4.184 for the thermochemical calorie used here. A food Calorie is 1,000 of them, 4,184 J.
- About 100,000 — by definition 100,000 of the older 59 °F BTU, which is 99,976 of the international BTU this page uses.
- 418.4 kJ: 100 × 4.184.
- A 100 W bulb left on for 10 hours, or a 2 kW kettle boiling for 30 minutes.
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