Convert Kilocalories to Microjoules
Convert Kilocalories (kcal) to Microjoules (µJ) instantly and accurately.
Conversion Formula
µJ = kcal × 4184000000
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 Microjoules
A microjoule (µJ) is 10⁻⁶ J - the scale of precision laser ablation, ESD damage events, and individual LIDAR pulses. LASIK eye surgery delivers 0.5-2 µJ per pulse at 193 nm, ablating ~0.25 µm of corneal tissue per pulse. ESD events that destroy IC gates correspond to 1-1,000 µJ; the Human Body Model test discharges ~500 µJ at 2 kV. Q-switched microchip laser pulses for rangefinding are 1-100 µJ. The kinetic energy of a 1 mg grain of sand falling 10 cm is mgh ≈ 0.98 µJ. 1 µJ = 10⁻⁶ J.
Quick Reference Table
| Kilocalories (kcal) | Microjoules (µJ) |
|---|---|
| 1 kcal | 4.184 × 109 µJ |
| 2 kcal | 8.368 × 109 µJ |
| 5 kcal | 2.092 × 1010 µJ |
| 10 kcal | 4.184 × 1010 µJ |
| 25 kcal | 1.046 × 1011 µJ |
| 50 kcal | 2.092 × 1011 µJ |
| 100 kcal | 4.184 × 1011 µJ |