Rate of energy transfer across electrical, mechanical, thermal and HVAC systems.
All factors come from the central conversion registry.
| Unit | Symbol | System | Definition |
|---|---|---|---|
| Watt | W | SI | 1 W = 1 J/s |
| Kilowatt | kW | SI | 1 kW = 1000 W |
| Milliwatt | mW | SI | 1 mW = 0.001 W |
| Erg per Second | erg/s | CGS | 1 erg/s = 10⁻⁷ W |
| Calorie per Second | cal/s | Thermochemical | 1 cal/s = exactly 4.184 W |
| Foot-pound per Minute | ft·lbf/min | US customary | 1 ft·lbf/min ≈ 0.02259696580552334 W |
| BTU per Hour | BTU/h | Thermal | 1 BTU/h ≈ 0.2930710701722222 W |
| Metric Horsepower | PS | Metric | 1 PS = 735.49875 W |
| Mechanical Horsepower | hp | US customary | 1 hp ≈ 745.6998715822702 W |
| Ton of Refrigeration | TR | HVAC | 1 TR ≈ 3,516.8528420667 W |
| Megawatt | MW | SI | 1 MW = 10⁶ W |
| Gigawatt | GW | SI | 1 GW = 10⁹ W |
Power is the rate of energy transfer. Watts are joules per second, so power conversions remain separate from energy conversions even when the unit names are commonly used together.
The interactive calculator, reference table and indexed pair pages all read from the same conversion registry, so unit definitions and formulas stay synchronized.