Convert Picojoules to Calories
Convert Picojoules (pJ) to Calories (cal) instantly and accurately.
Conversion Formula
cal = pJ × 2.390057361e-13
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 Calories
A calorie (cal) - the thermochemical calorie - is exactly 4.184 J, defined as the heat to raise 1 g of water by 1°C. Standard since 1954. The calorie is the fundamental unit of heat measurement in thermochemistry: glucose combustion releases 669.9 kcal/mol; water vaporisation requires 539.7 cal/g. Bond dissociation energies in quantum chemistry are often quoted in kcal/mol. Note: the dietary Calorie (capital C) on food labels is 1 kcal = 4,184 J - a factor-of-1,000 difference that causes persistent confusion. 1 cal = 4.184 J = 1.163 × 10⁻³ Wh.
Quick Reference Table
| Picojoules (pJ) | Calories (cal) |
|---|---|
| 1 pJ | 2.39 × 10-13 cal |
| 2 pJ | 4.78 × 10-13 cal |
| 5 pJ | 1.195 × 10-12 cal |
| 10 pJ | 2.39 × 10-12 cal |
| 25 pJ | 5.975 × 10-12 cal |
| 50 pJ | 1.195 × 10-11 cal |
| 100 pJ | 2.39 × 10-11 cal |