Energy Converter

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

kJ = J × 0.001

Energy units and how they relate

The calorie here is the thermochemical calorie (exactly 4.184 J); a food "Calorie" is one kilocalorie. One kilowatt-hour is exactly 3.6 MJ. The BTU is the International Table BTU (1,055.05585262 J).

UnitSymbolEquals in joules
1 jouleJ1 J
1 kilojoulekJ1,000 J
1 caloriecal4.184 J
1 kilocaloriekcal4,184 J
1 watt-hourWh3,600 J
1 kilowatt-hourkWh3,600,000 J
1 BTUBTU1,055.055853 J
1 foot-poundft·lbf1.355817948 J

Popular energy conversions

joules to kilojoulesjoules to caloriesjoules to kilocaloriesjoules to kilowatt-hourskilojoules to jouleskilojoules to calorieskilojoules to kilocalorieskilojoules to kilowatt-hourscalories to joulescalories to kilojoulescalories to kilocaloriescalories to kilowatt-hourskilocalories to jouleskilocalories to kilojouleskilocalories to calorieskilocalories to kilowatt-hourskilowatt-hours to jouleskilowatt-hours to kilojouleskilowatt-hours to calorieskilowatt-hours to kilocalories

Frequently asked questions

How accurate is this energy converter?

It uses the exact defined conversion factors for each unit and shows results to 10 significant digits. The calorie here is the thermochemical calorie (exactly 4.184 J); a food "Calorie" is one kilocalorie. One kilowatt-hour is exactly 3.6 MJ. The BTU is the International Table BTU (1,055.05585262 J).

How do I convert joules to kilojoules?

Enter the value, choose joules in the "From" list and kilojoules in the "To" list. For example, 1 joule equals 0.001 kJ.

Is the converter free?

Yes. It is free, needs no sign-up and runs entirely in your browser, so it also works offline once the page has loaded.

Related tools

Power ConverterConvert power: watts, kilowatts, megawatts, mechanical and metric horsepower and BTU per hour. Fuel Economy ConverterConvert fuel consumption between liters per 100 km, kilometers per liter, US mpg and UK mpg. Angle ConverterConvert angles: degrees, radians, gradians, arcminutes, arcseconds and full turns. Frequency ConverterConvert frequency: hertz, kilohertz, megahertz, gigahertz and revolutions per minute. Force ConverterConvert force: newtons, kilonewtons, pounds-force, kilograms-force and dynes. Currency ConverterConvert between 160+ world currencies with daily updated exchange rates.