Kilojoules to Joules Converter
kJ → J · ⚡ Energy
1 Kilojoules = 1,000 Joules
How to convert Kilojoules to Joules
To convert Kilojoules to Joules, multiply the value in Kilojoules by 1,000. For example, 5 kJ = 5,000 J.
If you need to convert from Kilojoules to Joules, the key figure to remember is that one Kilojoules equals 1,000 Joules. This page gives you a live calculator, a full reference table, and the underlying formula so you can convert kJ to J with complete confidence.
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 Joules
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 Joules values
The most frequently searched conversions are 1 Kilojoules = 1,000 Joules, 5 Kilojoules = 5,000 Joules, 10 Kilojoules = 10,000 Joules, and 100 Kilojoules = 100,000 Joules. The full table further down covers every common value, and the calculator handles any number you need in between.
Pro tip: When comparing appliance efficiency or heating costs, convert everything to kilowatt-hours first, since that's the unit your utility bill uses — it makes the real-world cost immediately comparable.
Kilojoules to Joules — Conversion Table
| Kilojoules (kJ) | Joules (J) |
|---|---|
| 0.1 kJ | 100 J |
| 0.25 kJ | 250 J |
| 0.5 kJ | 500 J |
| 1 kJ | 1,000 J |
| 2 kJ | 2,000 J |
| 5 kJ | 5,000 J |
| 10 kJ | 10,000 J |
| 25 kJ | 25,000 J |
| 50 kJ | 50,000 J |
| 100 kJ | 100,000 J |
| 250 kJ | 250,000 J |
| 500 kJ | 500,000 J |
| 1000 kJ | 1,000,000 J |