Energy Converter

Joules, calories, kilowatt-hours, and more converted exactly.

Quick answer: Convert energy units online. Free tool to calculate Joules, calories, and kilowatt-hours accurately for science and fitness.

Joules → Kilojoules0.001

exact international definitions — computed locally

Convert energy across scientific, nutritional, and electrical units, from joules to food calories to kilowatt-hours.

How it works

  1. Select the initial energy format and the format you want to translate to.
  2. Input your energy value.
  3. Read the converted result.

Frequently asked questions

Is a food Calorie the same as a calorie?

No — the dietary Calorie (capital C) is 1000 small calories, i.e. a kilocalorie. This trips up many conversions.

How many joules in a kWh?

Exactly 3.6 million (3,600,000 J), since 1 watt for 1 hour is 3600 J.

Where are these units used?

Joules in physics, calories in nutrition, kWh on electricity bills.

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