How many joules are in one calorie?

One calorie equals 4.184 J. The formula is J = cal × 4.184.

How do I convert calories to joules?

Multiply the value in calories by 4.184. For example, 100 × 4.184 = 418.4 — so 100 cal = 418.4 J.

Pair · linear · factor 4.184

calories to joules

calJ

Active unit

calories · ≈ 418.4 J (base)

All units

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calcalorie100

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Frequently asked questions

A glowing emerald doughnut with a battery-and-lightning symbol at its centre, wrapped in a geometric grid, against a cosmic nebula in violet and magenta

Energy

How much energy is in a doughnut — calories, joules and kilowatt-hours

A calorie on your plate, a joule in the lab and a kilowatt-hour on your electricity bill all describe exactly the same thing: the ability to do work. One traditional doughnut holds about 407 watt-hours of energy — enough to run an efficient LED for more than a day, or charge a smartphone nearly 24 times. Here is how a single pastry ties together nutrition, physics and your power bill.

13 min