RapidCheck

Energy Converter

Convert joules, calories, kilowatt-hours and BTU instantly.

Last updated: 8 Aug 2026

Quick answer

To convert energy, enter a value and choose the units — for example, 1 kilocalorie = 4184 joules, and 1 kilowatt-hour = 3.6 million joules. This converter handles joules, calories, kcal, watt-hours, kWh and BTU, instantly.

Convert energy between joules, calories, kilocalories, watt-hours, kilowatt-hours and BTU instantly — useful for nutrition, electricity bills and physics.

How to convert energy units

  1. 1 Enter the energy value.
  2. 2 Choose the units to convert from and to.
  3. 3 The result updates instantly.

Frequently asked questions

How many joules in a calorie?
One (small) calorie equals 4.184 joules; one kilocalorie (food Calorie) equals 4184 joules.
How many joules in 1 kWh?
One kilowatt-hour equals 3,600,000 joules (3.6 megajoules).
Is a food Calorie a kilocalorie?
Yes — the "Calorie" on food labels is actually a kilocalorie (kcal).

Related checkers

Pressure Converter Calorie Calculator