About the project
kJ.sk is a Slovak converter of energy from kilojoules to kilocalories and back. You type into either field and the other one updates at once. The rule is 1 kcal = 4.184 kJ. The site also shows conversion tables for kJ to kcal and kcal to kJ.
The Potraviny (Foods) section lists energy values of 330 foods per 100 g and per serving. Each food shows its nutrition values and you can enter your own weight. The data come from the public USDA FoodData Central database, and each food has its FDC ID.
Three calculators work out daily energy intake, energy burned during activity and the energy of a meal. Articles explain the difference between kJ and kcal, how to read a label, the energy of drinks and the energy balance when losing weight. The calculators are only indicative and do not replace the advice of a doctor or dietitian.
What you will find
- Converter (Prevodník)
- kJ to kcal
- kcal to kJ
- Foods (Potraviny)
- Ranking: most kJ
- Ranking: least kJ
- Calculators (Kalkulačky)
- Daily intake and BMR
- Burning during activity
- Energy of a meal
- Articles (Články)
How to search
- On the home page enter a value in kJ or kcal and the other field converts by itself.
- For common values open the kJ to kcal or kcal to kJ tables.
- In the Foods section pick a food and enter your own weight.
- In the Calculators section work out daily intake, energy burned during activity or the energy of a meal.
- In the Articles section read how to read a label or how many kJ you need per day.
Frequently asked questions
How does kJ.sk convert kJ to kcal?
The rule is 1 kcal = 4.184 kJ. You multiply kcal by 4.184 and divide kJ by it. For a quick estimate, multiply or divide by four.
Where does the food data on kJ.sk come from?
The data come from the public USDA FoodData Central database. Each food shows its FDC ID.
What calculators does kJ.sk have?
There are three: daily energy intake with basal metabolism, energy burned during activity and the energy of a meal. The formulas are published and the results are indicative.
Why does a package show both kJ and kcal?
Regulations require energy to be given in both kJ and kcal. It is one energy expressed in two units.
