Converters

Energy Converter

Convert energy accurately between joules, kilojoules, megajoules, watt-hours, kilowatt-hours, thermochemical calories and International Table Btu.

Example: an energy use of 2.5 kilowatt-hours. How many megajoules is that?

Energy

From To

Result 9 MJ 2.5 kWh = 9 MJ

One-unit equivalent 1 kWh = 3.6 MJ A quick way to understand the relationship between the two units.

✓ Conversion factors match data and definitions from the National Institute of Standards and Technology (NIST)

How is the conversion calculated?

The value is converted to joules exactly, then to the requested unit. For example, 1 kilowatt-hour = 3,600,000 joules exactly.

This calculation runs in your browser. Your values are not sent to our server.

How it works

Enter the energy value, then choose the current unit and the unit you want to convert to.
Example: 2.5 kilowatt-hours equals exactly 9 megajoules.
Use the swap button to reverse the units without re-entering the value.
The converter uses the joule as its internal reference unit and applies exact definitions where available.
Calories and Btu have multiple historical definitions, so this tool labels the thermochemical calorie and International Table Btu explicitly instead of mixing them.

How many joules are in 1 kilowatt-hour?

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

How many megajoules are in 1 kilowatt-hour?

1 kilowatt-hour equals exactly 3.6 megajoules.

How many joules are in 1 thermochemical kilocalorie?

1 thermochemical kilocalorie equals exactly 4,184 joules.

How many joules are in 1 International Table Btu?

1 International Table Btu equals exactly 1,055.05585262 joules.

Why does the tool specify the calorie and Btu type?

Several calorie and Btu definitions exist. Naming the exact definition prevents small but real conversion differences.