Calorie-counting apps are built around Calories, but if you live somewhere that labels food in kilojoules, you’ll constantly be moving between the two. Get the setup right once and it becomes effortless.
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Option 1: Switch Your App To Kilojoules
Many popular trackers, including MyFitnessPal and Cronometer: let you change the energy unit to kilojoules in their settings. Look for a section called Units, Energy or Preferences. Once switched:
- your daily goal is shown in kJ;
- food entries display in kJ;
- you can type kJ values straight from labels.
Menus and settings change over time, so if you can’t find the option, search your app’s help pages for “kilojoules”. Step-by-step guides: MyFitnessPal, Apple Watch and iPhone Health, Fitbit, Samsung Health, Garmin and Lifesum.
Option 2: Keep Calories And Convert
If your app doesn’t support kJ, or you prefer Calories:
- Convert your target once. Divide your daily kJ goal by 4.184. For example, 7,500 kJ = 1,793 Calories.
- Convert labels as you log. Divide the label’s kJ by 4.184, or use our kJ to calories converter.
- Be consistent. Never mix kJ and Calories in the same day.
Logging A kJ Label Accurately
When you add a food manually:
- Use the per 100 g figure from the label.
- Set the serving size in the app to 100 g.
- Weigh what you actually eat and log that weight, the app will scale it.
This avoids errors from unrealistic “per serve” sizes. The food label calculator shows the same maths if you want to double-check.
Checking Database Entries
User-created entries in food databases can be wrong, sometimes a kJ value has been entered as Calories, making a food look four times more energy-dense. Warning signs:
- a 100 g apple showing about 218 Calories (it should be about 52 Calories, or 218 kJ);
- two entries for the same product that differ by roughly 4.2 times.
When in doubt, compare with the label or with our food kJ chart.
Handling Exercise In The App
Apps and watches often add “earned” exercise Calories to your daily allowance. Estimates can be generous, so many people:
- eat back only a portion of exercise energy, or
- set an activity level that already includes regular exercise, and ignore the add-on.
Pick one approach and stick with it.
Quick Conversion Reference
| Kilojoules | Calories |
|---|---|
| 5,000 kJ | 1,195 kcal |
| 6,000 kJ | 1,434 kcal |
| 7,000 kJ | 1,673 kcal |
| 7,500 kJ | 1,793 kcal |
| 8,000 kJ | 1,912 kcal |
| 8,700 kJ | 2,079 kcal |
| 10,000 kJ | 2,390 kcal |
FAQ
Can I change MyFitnessPal to kilojoules?
Yes, MyFitnessPal lets you choose kilojoules as the energy unit in its settings. The exact menu location can change between app versions.
Should I track in kJ or Calories?
Whichever matches the labels you read most often. If your food is labelled in kJ, tracking in kJ avoids constant conversion.
Why does an app entry show four times too many Calories?
Someone probably entered the kJ value in the Calorie field. Check the label and use a verified entry.