Convert kilocalories to kilojoules

1 kcal=4.184kJ

Use the converter below to change any kilocalories value into kilojoules instantly — with formula, conversion table, and real-world examples.

You have

Equals

4.184

Conversion formula

Forward

kilojoules = kilocalories × 4.184

Reverse

kilocalories = kilojoules × 0.239

Example: 10 kcal × 4.184 = 41.84 kJ.

About both units

From

Kilocalorie

kcal

The kilocalorie equals 1000 small calories or 4184 joules. This is the nutrition "Calorie" (capital C in some US labels). EU and UK labels always say kcal; US labels say Calories. Adult daily intake is about 2000 kcal.

Real-world: Adult daily intake: ~2000 kcal. Banana: 90 kcal. Big Mac: 550 kcal. 30 min running: ~300 kcal burned.

Read full kilocalorie reference →

Kilojoule

The kilojoule equals 1000 joules. Used on European nutrition labels (required by EU law alongside kcal), for mechanical work specifications, and some engineering contexts. A 100 g chocolate bar contains about 2100 kJ.

Real-world: 100 g chocolate: ~2100 kJ. EU daily intake (adult): ~8400 kJ. Tesla Model 3 battery: ~270 MJ = 270,000 kJ.

Read full kilojoule reference →

Kilocalorie to Kilojoule conversion table

Common kilocalories to kilojoules values for quick reference.

Kilocalorie (kcal)	Kilojoule (kJ)
1 kcal	4.184 kJ
10 kcal	41.84 kJ
100 kcal	418.4 kJ
500 kcal	2,092 kJ
1,000 kcal	4,184 kJ
5,000 kcal	20,920 kJ
10,000 kcal	41,840 kJ
50,000 kcal	209,200 kJ
100,000 kcal	418,400 kJ
500,000 kcal	2,092,000 kJ

Tips & common mistakes

Quick tips

1 kcal = 4.184 kJ.
US "Calorie" (with capital C) = 1 kcal.
Apps and smartwatches track active energy in kcal.

Avoid these

Reading food "Calories" as gram calories — factor of 1000 off.
Treating all calorie values as comparable — macros (fat, protein, carb) differ in energy density.
Counting kcal without portion size leads to underestimates.

Frequently asked questions

How many kilojoules in a kilocalorie?

One kilocalorie equals 4.184 kilojoules.

How do I convert kilocalories to kilojoules?

Multiply the kilocalorie value by 4.184 to get the equivalent in kilojoules.

What is 100 kilocalories in kilojoules?

100 kilocalories equals 418.4 kilojoules.

Is a kilocalorie bigger than a kilojoule?

Yes. 1 kilocalorie equals 4.184 kilojoules, so one kilocalorie is larger.

How to convert kilocalories to kilojoules without a calculator?

Multiply by 4.18 for a quick estimate; use a calculator for precise results.

Related energy conversions

📊 See full comparison matrix →

Conversions in other categories

WeightKilogram → Pound LengthKilometer → Mile TemperatureCelsius → Fahrenheit VolumeLiter → US Gallon AreaSquare Meter → Square Foot SpeedKilometer per Hour → Mile per Hour PressureBar → Pound per Square Inch PowerKilowatt → Mechanical Horsepower