Energy Converter

Convert energy between joules, calories, kilowatt-hours, BTU, and more.

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  • ⚡ Converted in your browser
  • ✅ No account required

Energy Converter: The Complete Guide

Convert energy instantly. Switch between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, and foot-pounds, and see the conversion rate both ways.

Who the Energy Converter is for

Students, engineers, and anyone converting energy between scientific and everyday units.

How to use the Energy Converter

  1. Type your values into the fields above — pick your currency or units where the calculator offers them.
  2. Results update automatically as you type; there's no submit button and nothing is sent to a server.
  3. Adjust any input to compare scenarios, then copy the result with a single click.

How it works

Each unit has a fixed size in joules. The value is converted to joules, then to the target unit: result = value × (from-unit joules) ÷ (to-unit joules).

Features

  • Joules, calories, kWh, BTU
  • Food & electrical energy
  • Two-way conversion rate
  • Instant result

Energy units

Energy comes in many units: joules in physics, (kilo)calories on food labels, kilowatt-hours on electricity bills, and BTU in heating and cooling. They all measure the same thing. One food Calorie is a kilocalorie (4,184 joules), and one kWh is 3.6 million joules. This converter ties them all together.

Frequently Asked Questions

Is a food Calorie the same as a calorie?

A food 'Calorie' (capital C) is actually a kilocalorie — 1,000 small calories. The converter includes both calories and kilocalories.

How many joules in a kilowatt-hour?

Exactly 3,600,000 joules (3.6 megajoules), since a kilowatt sustained for one hour delivers that much energy.

Is this calculator free and private?

Yes. It's completely free with no signup, and every calculation runs locally in your browser, so your numbers never leave your device.