Energy Converter
Convert energy between joules, calories, kWh, BTU and more.
Results update as you type.
About this calculator
An energy converter changes a quantity of energy between joules and kilojoules, calories and kilocalories (food Calories), watt-hours and kilowatt-hours, the BTU and the foot-pound. All values convert through the joule.
Frequently asked questions
How many joules are in a food Calorie?
A food Calorie is a kilocalorie, which equals 4,184 joules (4.184 kJ). So a 200 Calorie snack holds about 837 kJ of energy.
How many joules in a kilowatt-hour?
One kilowatt-hour is 3.6 million joules (3.6 MJ), because it is 1,000 watts sustained for 3,600 seconds. It is the unit your electricity bill is measured in.
What is a BTU?
A British Thermal Unit is the energy to raise one pound of water by 1 °F, about 1,055 joules. It is common in heating and air-conditioning ratings.
Results are estimates for general guidance only, not financial, medical or tax advice.