Energy Converter — Free Online Tool

Convert Joules, kWh, BTU, calories, electronvolts and ergs. Energy Converter is a free online tool from the ToolsRift Unit Converters collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.

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How to use Energy Converter

  1. Open the Energy Converter above — it loads instantly, no account needed.
  2. Enter or upload your input. Everything is processed locally on your device.
  3. Get your result immediately and copy or download it with one click.

Frequently asked questions

How many joules in a kWh?

1 kilowatt-hour = 3,600,000 joules (3.6 megajoules).

How many calories in a joule?

1 calorie (small cal) = 4.184 joules; 1 kilocalorie (food Calorie) = 4,184 joules.

What is a BTU?

A British Thermal Unit equals about 1,055.06 joules — commonly used for air conditioner and heater ratings.

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