Calorie to Kilojoule Converter
Energy · unit-converter
Convert Calorie to Kilojoule with fixed input and output units, a step-by-step formula line, and reference tables. Factors are joule-based; food energy uses thermochemical calories. The full Energy Converter also includes MMBtu, toe, thermal kWh, and MeV/GeV.
Calculator
From: Calorie (cal)
To: Kilojoule (kj)
About Calorie
The small calorie (cal) is 4.184 J in this converter (thermochemical). Do not confuse with the dietary kilocalorie (kcal).
About Kilojoule
One kilojoule is 1,000 J. Scientific and engineering contexts often use kJ alongside joules.
How to convert calories to kilojoules
1 calorie is equal to 0.004184 kilojoule when both are expressed in joule-equivalents:
1 cal = (4.184 J ÷ 1,000 J) kj = 0.004184 kj
Each calorie is defined as 4.184 J and each kilojoule as 1,000 J in this tool, so one cal equals 4.184 ÷ 1,000 kj = 0.004184 kj.
Let d(cal) be the numeric amount in Calorie (cal), and d(kj) the amount in Kilojoule (kj). Then:
d(kj) = d(cal) × (4.184 / 1,000)
Equivalently, divide by how many cal fit into one kj (joules per kj divided by joules per cal):
d(kj) = d(cal) ÷ 239.0057361376673
Or: kilojoule = calorie ÷ 239.0057361376673
Examples
Example #1: Convert 1 cal to kilojoule
1 cal = 1 cal × (4.184/1,000) kj = 0.004184 kj
1 cal = 1 cal ÷ 239.0057361376673 = 0.004184 kj
Example #2: Convert 10 cal to kilojoule
10 cal = 10 cal × (4.184/1,000) kj = 0.04184 kj
10 cal = 10 cal ÷ 239.0057361376673 = 0.04184 kj
Summary
To convert Calorie to Kilojoule, multiply the value in cal by the ratio of joules per cal divided by joules per kj. Equivalently: value_kj = value_cal × (4.184 / 1000). Numerically, 1 cal equals 0.004184 kj.
Relationship context
You are converting between food / nutrition energy (calories) (Calories) and SI energy (joules) (Kilojoules). All values are mapped through joules first. The numeric factor is 4.184000e-3.
Conversion tables
| Calorie (cal) | Kilojoule (kj) |
|---|---|
| 0.1 | 0.0004184 |
| 1 | 0.004184 |
| 2 | 0.008368 |
| 3 | 0.012552 |
| 4 | 0.016736 |
| 5 | 0.02092 |
| 6 | 0.025104 |
| 7 | 0.029288 |
| 8 | 0.033472 |
| 9 | 0.037656 |
| Calorie (cal) | Kilojoule (kj) |
|---|---|
| 10 | 0.04184 |
| 20 | 0.08368 |
| 30 | 0.12552 |
| 40 | 0.16736 |
| 50 | 0.2092 |
| 60 | 0.25104 |
| 70 | 0.29288 |
| 80 | 0.33472 |
| 90 | 0.37656 |
| 100 | 0.4184 |