The calculation converts your value to joules first, then divides by the target unit factor. The distinction between a scientific calorie and a food Calorie matters: one food Calorie is one kilocalorie, or 1,000 small calories. All calculations run in your browser, so values are not uploaded.
Private browser utility / Converters
Free Energy Converter
Runs entirely in your browser - no upload, no sign-up.
Food Calories use kcal. Kilowatt-hours measure energy; kilowatts measure power. Signed values are supported for energy changes.
Converted energyEnter an energy value to compare all 13 units
How do you convert energy units?
Enter an amount, choose its current unit, and select the energy unit you need. This energy converter updates instantly between joules, kilowatt-hours, calories, BTU, therms, foot-pounds and electronvolts. It also shows every equivalent together, making electricity, nutrition, heating and physics values easier to compare.
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How to use
- 01Enter the energy
Type a value with a decimal point, decimal comma, or scientific notation. Signed values are accepted for energy changes.
- 02Choose the source unit
Select the unit attached to your original value, such as kWh, kcal, BTU or eV.
- 03Choose the target unit
Pick the energy unit you need. The main answer, formula and all-units table update live.
- 04Copy or reverse it
Copy the complete conversion, or swap the source and target units without retyping the value.
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Who it's for
- Households and energy analysts translating electricity use between kWh, MWh, megajoules and gigajoules.
- Nutrition students comparing food Calories in kcal with the kilojoules printed on international labels.
- HVAC and heating teams converting BTU or US therms to joules and kilowatt-hours while keeping the thermal unit definition clear.
- Physics students and engineers moving between joules, foot-pounds and electronvolts across very different scales.
- Researchers checking signed energy changes with scientific notation instead of manually tracking long exponents.
FAQ
Is this energy converter free?
Yes. The energy converter is free to use without registration, downloads or a normal-use limit. It performs each conversion locally in your browser, and you can convert any supported pair of energy units as often as needed.
Is my energy data uploaded?
No. The value and units stay in your browser and are not sent to a conversion service. The page already contains the conversion factors, so it can calculate the result locally without uploading your input.
Which energy units can I convert?
You can convert joules, kilojoules, megajoules, gigajoules, watt-hours, kilowatt-hours, megawatt-hours, thermochemical calories, kilocalories, International Table BTU, US therms, foot-pounds force and electronvolts. Every supported unit appears in the comparison table.
How many joules are in one kWh?
One kilowatt-hour equals exactly 3,600,000 joules, or 3.6 megajoules. A watt is one joule per second, so a kilowatt maintained for 3,600 seconds transfers 1,000 x 3,600 joules of energy.
What is the difference between calories and kilocalories?
One kilocalorie equals 1,000 small calories. Nutrition labels use the capitalized word Calorie to mean one kilocalorie, so a food value of 250 Calories should be entered as 250 kcal, not 250 cal. That equals 1,046 kilojoules.
How many BTU are in one kWh?
One kilowatt-hour is about 3,412.141633 International Table BTU. The converter uses 3,600,000 J per kWh and 1,055.05585262 J per BTU, preserving more precision internally than the displayed answer usually needs.
Are kW and kWh the same?
No. A kilowatt is a rate of power, while a kilowatt-hour is an amount of energy. A 2 kW appliance running for half an hour uses 1 kWh. Use this page for kWh; use a power converter for kW.
Can the converter handle electronvolts and scientific notation?
Yes. Electronvolts are included for atomic-scale energy, and inputs such as 2.5e6 are accepted. Very large or small results switch to scientific notation so long exponents remain readable without losing the unit.