Calories to Joules Converter

One calorie (small) equals 4.184 joules (J). To convert calorie (small)s to joules, multiply by 4.184; to go back the other way, multiply by 0.23900574 instead.

The converter above does it as you type and shows the working underneath, so you can check the arithmetic rather than take the number on trust.

What calorie (small)s and joules actually measure

Calorie (small) (cal) — A calorie raises one gram of water by one degree Celsius — 4.184 joules. Chemistry and physics. Note this is the small calorie, not the food one.

Joule (J) — The joule is the SI unit of energy — one watt for one second. Physics, mechanical work and food energy in most of the world.

Calories to Joules conversion table

The most common values, worked out in advance. Anything not listed can be typed straight into the converter.

How to convert calorie (small)s to joules by hand

Multiply the number of calorie (small)s by 4.184.

For example, 25 cal × 4.184 = 104.6 J.

Going the other way, divide by 4.184 — or multiply by 0.23900574, which is the same thing and easier to do in your head.

Everything runs in your browser

There is no server involved in the calculation. The numbers you type never leave your device, nothing is logged, and the page keeps working with no connection once it has loaded. That is not a marketing line — it is simply how the tool is built, because a calculation like this has no reason to touch a network.