Convert Calories to Gigajoules
Convert Calories (cal) to Gigajoules (GJ) instantly and accurately.
Conversion Formula
GJ = cal × 4.184000000e-9
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.
About Gigajoules
A gigajoule (GJ) is 10⁹ J - the scale of fossil-fuel commodity volumes. One barrel of crude oil contains ~5.80 GJ; one metric tonne of hard coal ~29.3 GJ. Canadian energy bills express household consumption in GJ: average Canadian households use ~100-130 GJ/year. A 1 GW power plant at 33% efficiency burns ~10.9 GJ/h of fuel to generate 1 GWh = 3.6 GJ of electricity. Detonation of 1 tonne of TNT releases 4.184 GJ. 1 GJ = 10⁹ J = 277.78 kWh = 947,817 BTU = 9.4782 therms.
Quick Reference Table
| Calories (cal) | Gigajoules (GJ) |
|---|---|
| 1 cal | 4.184 × 10-9 GJ |
| 2 cal | 8.368 × 10-9 GJ |
| 5 cal | 2.092 × 10-8 GJ |
| 10 cal | 4.184 × 10-8 GJ |
| 25 cal | 1.046 × 10-7 GJ |
| 50 cal | 2.092 × 10-7 GJ |
| 100 cal | 4.184 × 10-7 GJ |