Energy Converter
Enter one energy value and instantly see useful equivalents for electricity, batteries, heat, appliances, engineering, and nutrition.
Browse conversion tools
This page uses HandyCalcHub's shared conversion engine. Visit the Converters hub to see current and future converter categories.
What this converter does
The Energy Converter changes one entered energy amount into several common units at the same time. It supports joules, kilojoules, megajoules, watt-hours, kilowatt-hours, British thermal units, small calories, and kilocalories.
How energy conversion works
Each unit is converted through a shared base unit: joules. For example, kilowatt-hours convert to joules using the exact relationship 1 kWh = 3,600,000 J. The result is then converted from joules into each target unit.
Calories need careful labeling. A small calorie, written cal, equals 4.184 J. A kilocalorie, written kcal, equals 1,000 small calories and is the food Calorie commonly shown on nutrition labels.
Worked example
If you enter 1 kWh, the converter shows 3,600,000 J, 3,600 kJ, 3.6 MJ, 1,000 Wh, about 3,412.141633 BTU, and about 860.4206501 kcal.
Useful conversion relationships
| Relationship | Value |
|---|---|
| 1 kJ | 1,000 J |
| 1 MJ | 1,000,000 J |
| 1 Wh | 3,600 J |
| 1 kWh | 3,600,000 J |
| 1 cal | 4.184 J |
| 1 kcal | 4,184 J |
| 1 kcal | 1,000 cal |
| 1 BTU | about 1,055.05585262 J |
When energy conversions are useful
Energy conversions are useful for electricity usage, utility bills, batteries, appliances, heating and cooling estimates, engineering calculations, heat output, and nutrition comparisons where calories and kilocalories need clear labels.
Frequently asked questions
How many joules are in a kWh?
One kilowatt-hour equals 3,600,000 joules.
How many watt-hours are in a kWh?
One kilowatt-hour equals 1,000 watt-hours.
What is the difference between calories and kilocalories?
A small calorie, written cal, is 4.184 joules. A kilocalorie, written kcal, is 1,000 small calories and is the food Calorie used on nutrition labels.
How many BTU are in a kWh?
One kilowatt-hour is about 3,412.141633 British thermal units.
Is a watt a unit of energy?
No. A watt is a unit of power, not energy. A watt-hour is a unit of energy. This distinction matters because power describes a rate, while energy describes an amount used or stored.