How do you convert kJ to kcal?
Divide kilojoules by 4.184. For a quick estimate, divide by 4 and take away about 4%: 2,000 kJ → 500 − 20 = 480 kcal, against an exact 478 kcal.
- 1 kJ
- 0.239 kcal
- 1,000 kJ
- 239.0 kcal
- 1 kcal
- 4.184 kJ
kJ to kcal table
| Kilojoules (kJ) | Kilocalories (kcal) |
|---|---|
| 1 | 0.2390057 |
| 2 | 0.4780115 |
| 3 | 0.7170172 |
| 4 | 0.9560229 |
| 5 | 1.195029 |
| 6 | 1.434034 |
| 7 | 1.67304 |
| 8 | 1.912046 |
| 9 | 2.151052 |
| 10 | 2.390057 |
| Kilojoules (kJ) | Kilocalories (kcal) |
|---|---|
| 12 | 2.868069 |
| 15 | 3.585086 |
| 20 | 4.780115 |
| 25 | 5.975143 |
| 30 | 7.170172 |
| 40 | 9.560229 |
| 50 | 11.95029 |
| 60 | 14.34034 |
| 75 | 17.92543 |
| 100 | 23.90057 |
Reading kilojoule labels
Food sold in Australia and New Zealand states energy in kilojoules, and EU labels list kilojoules before kilocalories. If you count Calories, divide the kJ figure by 4.184. A muesli bar at 600 kJ is about 143 kcal; a sandwich at 1,800 kJ is about 430 kcal.
Australian health campaigns use 8,700 kJ as the average adult's daily intake, close to the 2,000 kcal reference used on US labels and the 8,400 kJ reference in the EU. All three are averages for labeling, not personal targets.
Kilojoules in sport
Power meters on bikes and rowing machines count the work you put out in kilojoules. Because muscles turn only about a quarter of food energy into motion, the food energy burned is roughly four times the work, and the 4.184 factor brings the two figures close together. A 600 kJ ride burned roughly 600 kcal, give or take 15%.
Going the other way is on kcal to kJ. For portion weights on the same label, grams to oz does the conversion.
kJ to kcal questions
What fraction of a kilocalorie is one kilojoule?
About 0.239 kcal. Divide kilojoules by 4.184.
How many Calories does the 8,700 kJ daily figure stand for?
About 2,079 kcal. Australian labels use 8,700 kJ as the average adult daily intake.
How many Calories is 500 kJ?
About 119.5 kcal.
Why does my bike computer show kJ about equal to Calories burned?
The kJ figure is the mechanical work you did on the pedals. Your body is only about 20 to 25% efficient, so the food energy burned is roughly four times larger, and dividing by 4.184 to get kcal cancels most of that out. It is a rule of thumb, not a measurement.