Calories to Kilojoules Converter
cal → kJ · ⚡ Energy
1 Calories = 0.004184 Kilojoules
How to convert Calories to Kilojoules
To convert Calories to Kilojoules, multiply the value in Calories by 0.004184. For example, 5 cal = 0.02092 kJ.
Converting Calories (cal) to Kilojoules (kJ) is a frequent need, and the exact relationship is 1 cal = 0.004184 kJ. Whether you're working on a project, checking a specification, or just curious, the calculator above gives you the answer instantly for any value you enter.
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 Calories 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 Calories to Kilojoules values
The most frequently searched conversions are 1 Calories = 0.004184 Kilojoules, 5 Calories = 0.02092 Kilojoules, 10 Calories = 0.04184 Kilojoules, and 100 Calories = 0.4184 Kilojoules. 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.
Calories to Kilojoules — Conversion Table
| Calories (cal) | Kilojoules (kJ) |
|---|---|
| 0.1 cal | 0.0004184 kJ |
| 0.25 cal | 0.001046 kJ |
| 0.5 cal | 0.002092 kJ |
| 1 cal | 0.004184 kJ |
| 2 cal | 0.008368 kJ |
| 5 cal | 0.02092 kJ |
| 10 cal | 0.04184 kJ |
| 25 cal | 0.1046 kJ |
| 50 cal | 0.2092 kJ |
| 100 cal | 0.4184 kJ |
| 250 cal | 1.046 kJ |
| 500 cal | 2.092 kJ |
| 1000 cal | 4.184 kJ |