Convert between common energy units instantly
This energy converter supports nine common energy units: Joules (J), Kilojoules (kJ), Calories (cal), Food kilocalories (kcal), Watt-hours (Wh), Kilowatt-hours (kWh), British Thermal Units (BTU), foot-pounds (ft·lb), and electronvolts (eV). It is useful for physics, engineering, nutrition, and electrical energy calculations.
Select the energy unit you are starting with, enter the value, and click "Convert". The tool will display the equivalent energy in all supported units. For example, enter 1 kWh to see it equals 3.6 million Joules or about 3412 BTU.
A food calorie (kcal or large Calorie) equals 1000 small calories (cal). When you see "Calories" on a food label, it actually refers to kilocalories (kcal). This converter uses the scientific convention: 1 kcal = 1000 cal = 4184 Joules.
1 kilowatt-hour equals 3.6 million Joules. Multiply kWh by 3,600,000 to get Joules. For example, 2 kWh × 3,600,000 = 7,200,000 J (7.2 MJ). This is the standard conversion used for electricity billing and energy storage calculations.