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Convert between Joules, Calories, Watt-hours, and BTUs.

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Understanding Energy Conversion

Energy measures the capacity to do work or produce heat. The joule is the SI unit, while calories are used in nutrition, and kilowatt-hours measure electrical energy consumption.

Unit Type Unit Name Value in Joules (J)
Metric Joule (J) 1 J
Metric Kilojoule (kJ) 1,000 J
Metric Megajoule (MJ) 1,000,000 J
Nutrition Calorie (cal) 4.184 J
Nutrition Kilocalorie (kcal) 4,184 J
Electrical Watt-hour (Wh) 3,600 J
Electrical Kilowatt-hour (kWh) 3,600,000 J
Imperial BTU 1,055.06 J
Physics Electron Volt (eV) 1.602×10⁻¹⁹ J

Conversion Tip

Energy measures the capacity to do work. The joule is the SI unit, while calories and kilowatt-hours are common in nutrition and electricity.


Quick Reference

  • 1 kilojoule = 1,000 joules
  • 1 calorie = 4.184 joules
  • 1 kilocalorie (kcal) = 4,184 joules
  • 1 kilowatt-hour = 3.6 megajoules
  • 1 BTU = 1,055.06 joules
  • 1 electron volt = 1.602×10⁻¹⁹ joules
  • 1 watt-hour = 3,600 joules
  • 1 food calorie = 1 kilocalorie
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