Kilojoules to Watt-hours Converter

How to convert Kilojoules to Watt-hours

To convert Kilojoules to Watt-hours, multiply the value in Kilojoules by 0.27777778. For example, 5 kJ = 1.3888889 Wh.

The Kilojoules-to-Watt-hours conversion comes up often in everyday and professional contexts alike. With 1 kJ equal to 0.27777778 Wh, you can use the tool above for any value, or scan the table below for the most common Kilojoules amounts and their Watt-hours 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 Kilojoules and Watt-hours

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 Kilojoules to Watt-hours values

The most frequently searched conversions are 1 Kilojoules = 0.27777778 Watt-hours, 5 Kilojoules = 1.3888889 Watt-hours, 10 Kilojoules = 2.7777778 Watt-hours, and 100 Kilojoules = 27.777778 Watt-hours. The full table further down covers every common value, and the calculator handles any number you need in between.