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Energy Converter

Convert energy accurately between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU.

Convert instantly
Enter a value and choose the units. Your answer updates as you type.

Result

0.001 Kilojoule (kJ)

Quick reference
  • Joule (J)1 base units
  • Kilojoule (kJ)1000 base units
  • Thermochemical calorie (cal)4.184 base units
  • Kilocalorie (kcal)4184 base units
  • Watt-hour (Wh)3600 base units
  • Kilowatt-hour (kWh)3600000 base units
  • International BTU1055.05585262 base units

About the Energy Converter

Energy can describe food, electricity, heating, mechanical work, and scientific measurements. This converter uses joules as the SI base, the thermochemical calorie of exactly 4.184 joules, the international BTU, and watt-hours. For example, 1 kWh is 3,600,000 J. Keeping the units explicit prevents confusing power (rate of energy) with energy itself.

Use it to compare a kilowatt-hour on an electricity bill with joules, estimate heating energy in BTU, or convert nutrition labels—for example, a 500 kcal food label represents 2,092,000 J. The Power Converter handles watts and horsepower, while the Temperature Converter complements thermal calculations.

Frequently asked questions

How many joules are in a kilowatt-hour?

One kilowatt-hour equals exactly 3,600,000 joules.

Is a food calorie the same as a calorie?

A food Calorie (capital C) is a kilocalorie, equal to 1,000 thermochemical calories or 4,184 joules.

What BTU standard is used?

This converter uses the International Table BTU: approximately 1,055.05585262 joules.

Take this calculation further

Browse the converters calculators collection for more tools in this subject.

For a related calculation, use Length Converter to convert length instantly between millimeters, meters, kilometers, inches, feet, yards, miles, nautical miles, and more with precise standard factors. Alternatively, use Power Converter to convert power between watts, kilowatts, megawatts, mechanical horsepower, metric horsepower, and BTU per hour.

For the underlying method, read A Quick Guide to Temperature Conversion Formulas.