Convert Joules to Kilocalories
Convert Joules to Kilocalories instantly. 1 Joule (J) equals 0.000239 Kilocalories (kcal).
Joules to Kilocalories conversion table
| Joules (J) | Kilocalories (kcal) |
|---|---|
| 1 J | 0.000239 kcal |
| 2 J | 0.000478 kcal |
| 3 J | 0.000717 kcal |
| 5 J | 0.001195 kcal |
| 10 J | 0.00239 kcal |
| 20 J | 0.00478 kcal |
| 50 J | 0.01195 kcal |
| 100 J | 0.0239 kcal |
| 500 J | 0.1195 kcal |
| 1,000 J | 0.239 kcal |
1 Joule = 0.000239 Kilocalories · multiply Joules by 0.000239
About converting Joules to Kilocalories
Joules (J) and Kilocalories (kcal) are both units of energy, so converting between them is a single multiplication: multiply your Joules figure by 0.000239. Ten Joules comes to 0.00239 Kilocalories, and a hundred works out at 0.0239 Kilocalories.
Rule of thumb: going from Joules to Kilocalories divides, so the figure always shrinks — it takes about 4,184 Joules to make a single Kilocalory. If your answer came out bigger, you have the conversion the wrong way round.
What is a Joule?
The joule is the SI unit of energy and the reference every other energy unit here is defined against. One joule is one newton acting over one metre — push with a newton of force, move a metre, and you have spent a joule. It is named after James Prescott Joule, whose painstaking experiments established that heat and mechanical work are the same thing, measurable in the same units. That result sounds obvious now and was foundational then: it collapsed heat, motion and work into a single quantity called energy, which is why one unit can serve food, electricity, explosives and engines alike.
What is a Kilocalory?
A kilocalorie is a thousand small calories, and it is what people actually mean when they say "calories" about food. Every figure on a nutrition label, every count on a menu board and every target in a diet app is a kilocalorie, even where the label just prints "cal" — a 2,000-calorie day is 2,000 kcal, not 2,000 calories in the physicist’s sense. The convention of capitalising the food unit as Calorie was meant to mark that difference, but it survives mostly in textbooks. Most of the world prints both kJ and kcal on packaging; the United States prints calories alone, which keeps the ambiguity alive.
To put both in perspective: lifting an apple one metre takes about a joule, while a plain bagel runs to roughly 250 kilocalories.
The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Kilocalories to Joules converter, or browse all Energy converters.
Frequently asked questions
How many Kilocalories are in one Joule?
There are 0.000239 Kilocalories in one Joule.
How do I convert Joules to Kilocalories?
Multiply the number of Joules by 0.000239. For example, 10 Joules = 0.00239 Kilocalories.
What is 100 Joules in Kilocalories?
100 Joules is equal to 0.0239 Kilocalories.
How do I convert Kilocalories to Joules?
Multiply the Kilocalories value by 4,184 (or divide by 0.000239).
Is this Joules to Kilocalories conversion exact?
The definition is exact — Joules and Kilocalories are both fixed against the same base by international agreement — but the decimal shown here is rounded for readability, because the true ratio does not terminate. For engineering or scientific work, carry more decimal places than this page displays.
What is a Joule?
The joule is the SI unit of energy and the reference every other energy unit here is defined against. One joule is one newton acting over one metre — push with a newton of force, move a metre, and you have spent a joule. It is named after James Prescott Joule, whose painstaking experiments established that heat and mechanical work are the same thing, measurable in the same units. That result sounds obvious now and was foundational then: it collapsed heat, motion and work into a single quantity called energy, which is why one unit can serve food, electricity, explosives and engines alike.
What is a Kilocalory?
A kilocalorie is a thousand small calories, and it is what people actually mean when they say "calories" about food. Every figure on a nutrition label, every count on a menu board and every target in a diet app is a kilocalorie, even where the label just prints "cal" — a 2,000-calorie day is 2,000 kcal, not 2,000 calories in the physicist’s sense. The convention of capitalising the food unit as Calorie was meant to mark that difference, but it survives mostly in textbooks. Most of the world prints both kJ and kcal on packaging; the United States prints calories alone, which keeps the ambiguity alive.