Joules (J) to Kilocalories (kcal) Conversion
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
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 (J) | Kilocalories (kcal) |
|---|---|
| 0.1 J | 2.3900573613767E-5 kcal |
| 1 J | 0.00023900573613767 kcal |
| 2 J | 0.00047801147227533 kcal |
| 3 J | 0.000717017208413 kcal |
| 5 J | 0.0011950286806883 kcal |
| 10 J | 0.0023900573613767 kcal |
| 20 J | 0.0047801147227533 kcal |
| 30 J | 0.00717017208413 kcal |
| 50 J | 0.011950286806883 kcal |
| 100 J | 0.023900573613767 kcal |
| 1000 J | 0.23900573613767 kcal |