Convert Picojoules to Kilocalories
Convert Picojoules (pJ) to Kilocalories (kcal) instantly and accurately.
Conversion Formula
kcal = pJ × 2.390057361e-16
About Picojoules
A picojoule (pJ) is 10⁻¹² J - the scale of laser pulses in scientific instruments and chip-level capacitor storage. A 1 pF capacitor charged to 1 V stores exactly 0.5 pJ. Laser pulse energies in OCT and ultrafast spectroscopy are typically 1-1,000 pJ. Single-photon SNSPD detector dead-time dissipates 1-100 pJ per event. Phase-change memory cells (PCM, ReRAM) switch at 10-100 pJ per state transition, setting a lower bound on non-volatile memory energy efficiency. 1 pJ = 10⁻¹² J = 6.242 MeV.
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.
Quick Reference Table
| Picojoules (pJ) | Kilocalories (kcal) |
|---|---|
| 1 pJ | 2.39 × 10-16 kcal |
| 2 pJ | 4.78 × 10-16 kcal |
| 5 pJ | 1.195 × 10-15 kcal |
| 10 pJ | 2.39 × 10-15 kcal |
| 25 pJ | 5.975 × 10-15 kcal |
| 50 pJ | 1.195 × 10-14 kcal |
| 100 pJ | 2.39 × 10-14 kcal |