All Tools

Energy Converter

Convert between joules, calories, watt-hours, BTU, electron volts and more

Enter Energy

All Conversions

Key Formulas

1 cal = 4.184 J
1 kWh = 3,600,000 J
1 BTU = 1,055.06 J
1 eV = 1.602 × 10⁻¹⁹ J
Ad Space

Related Tools

Temperature Converter Weight Converter Speed Converter Data Storage Converter
Ad Space

How Energy Conversion Works

Energy measures the ability to do work. The joule (J) is the SI unit. Different fields use different units: physics (joules), nutrition (calories), electricity (watt-hours), HVAC (BTU).

Common Energy Units

Frequently Asked Questions

What is the difference between a calorie and a kilocalorie?
1 kcal = 1,000 cal. Food "Calories" (capital C) are kilocalories. When a food label says 100 Calories, it means 100 kcal.
How many joules are in a calorie?
1 cal = 4.184 joules. 1 kcal (food calorie) = 4,184 joules.
What is a BTU?
A BTU is the heat to raise 1 pound of water by 1°F. 1 BTU = 1,055.06 joules. Used in HVAC systems.
How do you convert watt-hours to joules?
Multiply watt-hours by 3,600 to get joules. 1 Wh = 3,600 J.

Go deeper

Read the SnoopTool guide behind this tool

The calculator gives you the number. These SnoopTool guides explain the method, the assumptions and the decision — with worked examples, data tables and FAQs.

Browse all SnoopTool guides →