Convert Kilocalories to Petajoules
Convert Kilocalories (kcal) to Petajoules (PJ) instantly and accurately.
Conversion Formula
PJ = kcal × 4.184000000e-12
About Kilocalories
A kilocalorie (kcal) - the food Calorie (capital C) on US and Canadian nutrition labels - is exactly 4,184 J. WHO recommends ~2,000-2,500 kcal/day for adults. Energy density of nutrients: fat 9 kcal/g, carbohydrate 4 kcal/g, protein 4 kcal/g, ethanol 7 kcal/g. Running at 10 km/h burns ~600-800 kcal/h. Standard free energy of ATP hydrolysis is approximately −7.3 kcal/mol (−30.5 kJ/mol). Pre-SI thermodynamic tables in the US and Japan use kcal/mol for reaction enthalpies. 1 kcal = 4,184 J = 4.184 kJ = 3.968 BTU = 1.163 Wh.
About Petajoules
A petajoule (PJ) is 10¹⁵ J - the national energy policy scale. IEA reports primary energy in PJ/year: Sweden ~600 PJ; Germany ~12,500 PJ; the United States ~93,000 PJ. World total primary energy supply is ~605,000 PJ = 605 EJ. The 1883 Krakatoa eruption released ~200 PJ ≈ 48 megatons TNT. A 1-megaton nuclear weapon releases 4.184 PJ. Global annual steel production embeds ~38,000-47,000 PJ of energy. 1 PJ = 10¹⁵ J = 277.78 GWh = 238.85 ktoe = 23.88 ktoe.
Quick Reference Table
| Kilocalories (kcal) | Petajoules (PJ) |
|---|---|
| 1 kcal | 4.184 × 10-12 PJ |
| 2 kcal | 8.368 × 10-12 PJ |
| 5 kcal | 2.092 × 10-11 PJ |
| 10 kcal | 4.184 × 10-11 PJ |
| 25 kcal | 1.046 × 10-10 PJ |
| 50 kcal | 2.092 × 10-10 PJ |
| 100 kcal | 4.184 × 10-10 PJ |