Kilocalories (kcal) to Joules (J) Conversion
Kilocalories
The kilocalorie (kcal), commonly called a "Calorie" (capital C) in nutritional contexts, is a unit of energy equal to exactly 4,184 joules. It represents the energy needed to raise 1 kg of water by 1 °C. In nutrition, all food energy values are expressed in kcal per gram: carbohydrates and protein provide 4 kcal/g; fat provides 9 kcal/g; alcohol provides 7 kcal/g. An average adult requires approximately 2,000–2,500 kcal per day to maintain body weight.
Joules
The joule (J) is the SI derived unit of energy, work, and heat, defined as the work done when a force of one newton displaces an object by one metre (J = N·m = kg·m²·s⁻²). Named after James Prescott Joule, who established the mechanical equivalent of heat in the 1840s, the joule unifies all forms of energy — mechanical, thermal, electrical, chemical, and nuclear — under one framework. One joule is small: lifting an apple (≈100 g) one metre requires about 1 joule, while a human at rest metabolises approximately 80 joules per second.
| Kilocalories (kcal) | Joules (J) |
|---|---|
| 0.1 kcal | 418.40 J |
| 1 kcal | 4,184.00 J |
| 2 kcal | 8,368.00 J |
| 3 kcal | 12,552.00 J |
| 5 kcal | 20,920.00 J |
| 10 kcal | 41,840.00 J |
| 20 kcal | 83,680.00 J |
| 30 kcal | 125,520.00 J |
| 50 kcal | 209,200.00 J |
| 100 kcal | 418,400.00 J |
| 1000 kcal | 4,184,000.00 J |
Frequently Asked Questions (FAQ)
How many joules are in 1 kilocalories?
1 kilocalories (kcal) is exactly 4,184.00 joules (J).
How do I convert kilocalories to joules?
Multiply the value in kilocalories by 4,184.00 to get the result in joules. Or use the converter above — type any number and see the result instantly.