Convert between Joule, Calorie, BTU, kWh and more energy units. Professional tool for physics, engineering, and energy calculations.
SI base unit of energy. 1 J = work done by 1 Newton force over 1 meter distance.
Food calorie. Energy needed to raise 1 kg water by 1°C. Used in nutrition labeling.
Electrical energy unit. Energy consumed by 1000W device running for 1 hour.
Traditional energy unit. Energy to raise 1 pound water by 1°F. Used in HVAC.
Atomic scale energy. Energy gained by electron accelerated through 1V potential.
CGS unit of energy. 1 erg = 10⁻⁷ joules. Used in physics and astronomy.
| Unit | Joules (J) | kcal | kWh | BTU | Common Use |
|---|---|---|---|---|---|
| 1 Joule | 1 | 2.39×10⁻⁴ | 2.78×10⁻⁷ | 9.48×10⁻⁴ | Physics calculations |
| 1 Calorie | 4.184 | 0.001 | 1.16×10⁻⁶ | 3.97×10⁻³ | Small scale energy |
| 1 Kilocalorie | 4,184 | 1 | 1.16×10⁻³ | 3.97 | Food energy |
| 1 kWh | 3.6×10⁶ | 860 | 1 | 3,412 | Electrical bills |
| 1 BTU | 1,055 | 0.252 | 2.93×10⁻⁴ | 1 | HVAC systems |
| 1 Therm | 1.055×10⁸ | 25,200 | 29.3 | 100,000 | Natural gas billing |
Fundamental energy conversion between SI and traditional units.
Energy = Power × Time. Base for electrical energy calculations.
Energy of motion. Fundamental physics equation.
Gravitational potential energy formula.
Energy required to change temperature.
Most famous physics equation. Nuclear energy basis.
| Energy Source | Energy (Joules) | Energy (kWh) | Comparison |
|---|---|---|---|
| Lightning bolt | 5×10⁹ J | 1.4 kWh | Powers LED bulb for 140 hours |
| TNT (1 kg) | 4.6×10⁶ J | 1.3 kWh | Typical household use for 1 hour |
| Gasoline (1 L) | 3.4×10⁷ J | 9.4 kWh | Car drives ~10 km |
| Food calorie | 4,184 J | 1.16×10⁻³ kWh | Raises 1kg water by 1°C |
| AA Battery | 5.4×10³ J | 1.5×10⁻³ kWh | Powers flashlight for hours |
90% efficient: 10% energy lost as heat
Input: 100 kWh → Output: 90 kWh
Modern industrial motors with variable frequency drives
LED: 80-90% efficient (lumens/watt)
CFL: 60-70% efficient
Incandescent: 5% efficient (95% heat)
Lithium-ion: 85-95% round-trip efficiency
Pumped hydro: 70-85% efficiency
Compressed air: 50-70% efficiency