Watt-hours to Kilojoules Converter

How to convert Watt-hours to Kilojoules

To convert Watt-hours to Kilojoules, multiply the value in Watt-hours by 3.6. For example, 5 Wh = 18 kJ.

The Watt-hours-to-Kilojoules conversion comes up often in everyday and professional contexts alike. With 1 Wh equal to 3.6 kJ, you can use the tool above for any value, or scan the table below for the most common Watt-hours amounts and their Kilojoules equivalents.

Energy conversions appear in nutrition, fitness, physics, utility bills, and engineering. The same quantity of energy can be expressed in joules, calories, kilowatt-hours, or BTU depending on the context.

Understanding Watt-hours and Kilojoules

The joule is the SI unit, but everyday contexts use others: food labels use kilocalories (often just called 'calories'), electricity bills use kilowatt-hours, and heating and cooling systems use BTU (British Thermal Units). One food calorie is actually a kilocalorie — 1,000 of the small physics calories — which is a frequent source of confusion.

How accurate is this conversion?

Energy conversions use standard definitions: 1 calorie = 4.184 joules, 1 kilowatt-hour = 3,600,000 joules, 1 BTU = 1,055.06 joules. These are internationally agreed values, making the conversions exact.

All conversion factors on ClearUnits are based on internationally recognised standards (the International System of Units, SI, and official definitions). Factors are reviewed for accuracy and the calculator uses full-precision values, rounding only the displayed result.

Quick reference: common Watt-hours to Kilojoules values

The most frequently searched conversions are 1 Watt-hours = 3.6 Kilojoules, 5 Watt-hours = 18 Kilojoules, 10 Watt-hours = 36 Kilojoules, and 100 Watt-hours = 360 Kilojoules. The full table further down covers every common value, and the calculator handles any number you need in between.