Energy converter (J, cal, kWh, BTU)
Convert energy units: joule, kilojoule, calorie, kilocalorie, watt-hour, kilowatt-hour, BTU, electronvolt and erg, with every conversion at once.
How to useEnergy unit conversion
1 cal = 4.184 J (thermochemical calorie) · 1 kWh = 3.6 MJ · 1 BTU = 1,055.06 J (international BTU).
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Energy converter (J, cal, kWh, BTU): what it is for
Type a value and choose the unit to see the same energy in joules, kilojoules, megajoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, electronvolts, ergs, foot-pounds and tonnes of oil equivalent. Useful for comparing electricity use, food calories, air conditioner capacity and physics exercises.
The conversion is done in your browser, with the official conversion factors for each unit.
How to use
- Type the value.
- Choose the source unit.
- See and copy the conversion you need.
When to use it
- Converting kWh from your electric bill into joules.
- Turning calories into kJ.
- Solving thermodynamics exercises.
Frequently asked questions
How many joules are in a calorie?
One thermochemical calorie is 4.184 J. The Calorie on food labels, with a capital C, is the kilocalorie: 4,184 J.
How do I convert kWh to joules?
1 kWh is the energy of 1,000 W for one hour: 1,000 × 3,600 s = 3,600,000 J, or 3.6 MJ.
What is a BTU?
It is the British thermal unit, used for air conditioner and furnace capacity (BTU per hour). 1 BTU is about 1,055 J or 0.293 Wh.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.