Convert Kilojoules to Megajoules
Convert Kilojoules (kJ) to Megajoules (MJ) instantly and accurately.
Conversion Formula
MJ = kJ × 0.001
About Kilojoules
A kilojoule (kJ) is exactly 1,000 J and is the standard energy unit for food and physical chemistry. EU, Australian, and NZ food labels are mandatory in kJ: recommended adult intake is ~8,400 kJ/day. Bond dissociation energies: C-H bond 413 kJ/mol; C=C double bond 614 kJ/mol; N≡N triple bond 945 kJ/mol. Specific heat of water: 4.184 kJ/(kg·K). A cyclist riding at 150 W for one hour expends 540 kJ. Charpy and Izod impact toughness tests record results in J and kJ. 1 kJ = 1,000 J = 239.0 cal = 0.94782 BTU = 0.27778 Wh.
About Megajoules
A megajoule (MJ) is 10⁶ J - the scale of fuel combustion in vehicles and kinetic energy of road traffic. Energy content: 1 L diesel ~34.9 MJ; 1 L petrol ~32.2 MJ. A 1,500 kg car at 100 km/h has KE = ½ × 1,500 × 27.78² ≈ 0.579 MJ; at 200 km/h it carries 2.31 MJ - explaining crash severity's quadratic speed dependence. A 60 kWh EV battery stores 60 × 3.6 = 216 MJ. Detonation of 1 kg TNT releases 4.184 MJ. Adults at rest metabolise ~6-9 MJ/day. 1 MJ = 10⁶ J = 239.0 kcal = 0.27778 kWh = 947.8 BTU.
Quick Reference Table
| Kilojoules (kJ) | Megajoules (MJ) |
|---|---|
| 1 kJ | 0.001 MJ |
| 2 kJ | 0.002 MJ |
| 5 kJ | 0.005 MJ |
| 10 kJ | 0.01 MJ |
| 25 kJ | 0.025 MJ |
| 50 kJ | 0.05 MJ |
| 100 kJ | 0.1 MJ |