Energy Converter
Convert joules, calories, kWh, BTU and more — electricity and diet friendly.
The Energy Converter translates between the units used for electricity bills, food labels, heating and physics: joules, kilojoules, watt-hours and kilowatt-hours on the electrical side; calories and kilocalories (the 'Calories' on food labels) on the dietary side; plus BTU, therms, foot-pounds and even electronvolts.
The most confusing pair is the calorie: the 'calorie' on food packaging is actually a kilocalorie (1,000 small calories), and exactly 4,184 joules — the same energy as a 4.184-kilowatt-second. Understanding that a 2,000-food-Calorie diet is 8.37 MJ of energy connects dieting, exercise and physics in one number. Electric bills quote kilowatt-hours: one kWh is 3.6 MJ, enough to run a 1,000 W appliance for an hour.
All conversions use the exact standard definitions and run locally in your browser — type 1 kWh and watch it become 3,600,000 J, 860.4 kcal, or 3,412 BTU.
Result
1 kWh = 3.6 MJ
1 kWh = 3.6 MJ
1 MJ = 0.277777777778 kWh
How to use the Energy Converter
- Type the energy value.
- Pick the from-unit (J, kJ, cal, kcal, Wh, kWh, BTU…).
- Pick the to-unit.
- Read the converted figure plus the unit rate.
- Swap to express the same energy in another unit, e.g. food Calories as kilojoules.
Frequently asked questions
How many joules are in a food Calorie?
Exactly 4,184. The 'Calorie' (capital C) on food labels is a kilocalorie: 1 kcal = 1,000 small calories = 4,184 J. A 2,000-Calorie daily intake is therefore 8.37 megajoules of energy.
How do I convert kWh to joules?
Multiply by 3.6 million: 1 kWh = 3,600,000 J. A kilowatt-hour is one kilowatt of power sustained for one hour (1,000 W × 3,600 s). This is how electricity meters and bills measure your usage.
What is a BTU?
The British thermal unit is the energy needed to raise one pound of water by one degree Fahrenheit — about 1,055 J. Air conditioners and heaters are still rated in BTU per hour in the US, while most of the world uses watts.
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