I see 1,800 kJ on a UK food label. How many calories is that?

1,800 ÷ 4.184 = 430 kcal. If you're tracking a US diet (typically 2,000 kcal/day), convert kJ labels to kcal for easy comparison.

My fitness tracker shows workouts in kJ burned. How do I convert to calories?

Divide kJ by 4.184. Example: a 630 kJ workout = 630 ÷ 4.184 = 150 calories. Most trackers let you toggle units, but the conversion is always the same.

Is there a quick mental conversion from kJ to calories?

Rough estimate: divide kJ by 4 for a ballpark. Example: 800 kJ ÷ 4 = 200 kcal (actual: 191 kcal). Slightly overestimated, but close enough for quick mental math.

Why do different countries use different calorie units?

Historical reasons. The US adopted food Calories (kcal) early; the SI system standardized kilojoules later. Most countries switched for international consistency, but the US hasn't. Learn more at [calories to joules](/energy/calories-to-joules/).

Kilojoules (kJ) to Kilocalories (kcal) Converter

Enter a value to instantly convert between energy units.

From

Precision4 dp

1 Kilojoule = 0.239 Kilocalorie

Key Formulas

Kilocalorie → Kilojoule

kJ = kcal × 4.184

Kilojoule → Kilocalorie

kcal = kJ × 0.239006

Kilowatt-Hour → Joule

J = kWh × 3600000

Joule → Kilowatt-Hour

kWh = J × 2.77778e-7

Formula

kcal = kJ ÷ 4.184

Kilojoules are the international standard for food energy (used on labels in Europe, UK, Australia, Canada). Kilocalories (food calories) are the US standard. This reverse conversion is essential for comparing international nutrition labels, fitness apps, and research studies. The difference can affect diet tracking. For the reverse, see [kilocalories to kilojoules](/energy/kcal-to-kj/).

Source: ISO 80000-5:2019 (Quantities and units—Thermodynamics)

Frequently Asked Questions

Real-World Examples

Can of soda. A 330mL soft drink is typically 400-500 kJ, or about 100 kcal on a US label.

400 kJ = 95.6 kcal

Small meal or snack. A sandwich and drink might be 1,000-1,200 kJ, or 240-290 food calories.

1000 kJ = 239 kcal

Daily reference intake (international). 8,400 kJ on a UK/EU food label = 2,000 kcal, the reference daily intake.

8400 kJ = 2008 kcal

Breakfast cereal serving. A typical bowl (600 kJ) = about 143 calories on a US label.

600 kJ = 143 kcal

kcal to kj kwh to joules joules to kwh btu to joules calories to joules

Kilojoules (kJ) to Kilocalories (kcal) Converter

Key Formulas

Formula

Frequently Asked Questions

Real-World Examples

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