Calories to kJ Converter (Quick & Easy)

Calories (kcal) to Kilojoules (kJ) Converter

Enter food calories or exercise burn to get instant kilojoules.

kcal
Quick Select:
Result in Kilojoules
0 kJ

1 kcal = 4.184 kJ

When you buy food in Australia or New Zealand, the package shows energy in kilojoules (kJ). But most fitness apps (like MyFitnessPal or Apple Watch) show energy in calories.

If you want to convert kilojoules to calories, you only need to remember one simple number: 4.184.

calories to kj

How to Convert Calories to kJ

To convert calories to kilojoules, multiply the calorie number by 4.184.

Example:

If a snack has 100 calories:

Kilojoules (kJ) = Calories (kcal) × 4.184

Easy Mental Trick (Without a Calculator)

If you are at the grocery store and don't have a calculator:

  1. Multiply the calories by 4.
  2. Add a tiny bit extra to your answer.

Example: For a 150-calorie snack:

150 × 4 = 600

Add a little extra = about 625 to 630 kJ.

Quick Calorie to kJ Table

Here is a simple guide for everyday foods and drinks:

Food or DrinkCaloriesKilojoules (kJ)
Black Coffee5 cal21 kJ
Medium Apple / Banana90 cal377 kJ
Regular Flat White Coffee120 cal502 kJ
Protein / Muesli Bar220 cal920 kJ
Avocado Toast (1 slice)350 cal1,464 kJ
Chicken & Rice Meal550 cal2,301 kJ
Pub Chicken Parmigiana950 cal3,975 kJ
Australian Daily Average2,079 cal8,700 kJ

Why Australian Food Packages Use Kilojoules

Australia uses the metric system, so food packets legally must list kilojoules (kJ).

However, fitness apps made in the USA use calories. This creates a mismatch when tracking food:

  • If your fitness app goal is 1,800 calories per 1,800 × 4.184 = 7,531 kJ
  • (aim for about 7,500 kJ on local food packages).
  • The standard 8,700 kJ number printed on Australian food boxes equals about 2,079 calories.

Converting Workout Calories to kJ

Smartwatches usually show calories burned during exercise. Here is what those numbers mean in kilojoules:

  • 100 cal burned (Short Walk) = 418 kJ
  • 250 cal burned (30-min Gym Session) = 1,046 kJ
  • 500 cal burned (Hard Run) = 2,092 kJ

Calorie vs. kcal vs. kJ: What is the Difference?

  • Calorie and kcal: On food boxes, "Calorie" and "kcal" mean the exact same thing. 200 Calories = 200 kcal.
  • Kilojoule (kJ): This is just another way to measure energy (like measuring distance in kilometers instead of miles).

Frequently Asked Questions (FAQs)

  1. How many kJ are in 1 Calorie?

    There are 4.184 kJ in 1 Calorie.

  2. How do I convert 500 Calories to kJ?

    Multiply 500 by 4.184. 500 × 4.184 = 2,092 kJ.

  3. What is 8,700 kJ in Calories?

    8,700 kJ is about 2,079 Calories. This is the average daily intake shown on Australian food panels.

  4. How do I change MyFitnessPal from Calories to kJ?

    Open the MyFitnessPal app, go to Settings > Edit Profile > Units, and change your Energy setting from Calories to Kilojoules. This makes tracking Australian food labels much easier.

  5. What is 1,500 calories in kJ?

    1,500 calories equals 6,276 kJ (1,500 × 4.184). This is a common daily intake target for weight management.

  6. What is 2,000 calories in kJ?

    2,000 calories equals 8,368 kJ ($2,000 \times 4.184$). This is close to the average daily intake used on international nutrition labels.

  7. What is 1,200 calories in kJ?

    1,200 calories equals 5,021 kJ (1,200 × 4.184). This is a common daily intake target used in structured low-calorie weight loss plans.

  8. What is 2,500 calories in kJ?

    2,500 calories equals 10,460 kJ (2,500 × 4.184). This is a standard daily intake level for active adults and muscle-building diets.