A power converter translates between watts, kilowatts, horsepower, BTU/hour, and other power units. Power is the rate of energy transfer or work done per unit time. Enter any value and see all equivalents instantly.
Power Unit Converter
Power Reference Values
| Device / Application | Watts | HP | BTU/hr |
|---|---|---|---|
| LED light bulb | 10 | 0.013 | 34.1 |
| Microwave oven | 750 | 1.01 | 2,559 |
| 1 mechanical horsepower | 745.7 | 1.000 | 2,545 |
| 1 ton of AC (12,000 BTU/hr) | 3,517 | 4.72 | 12,000 |
| Tesla Model S (max ~250 HP) | ~250,000 | ~335 | ~853,000 |
How to Convert Power Units
Power unit conversion is needed when comparing engines, selecting motors, calculating electricity consumption, and sizing HVAC systems. The SI unit is the watt (W), but horsepower (HP) is widely used in automotive contexts, and BTU/hr in HVAC.
Step 1: Key Relationships
1 mechanical HP = 745.7 W = 0.7457 kW. 1 metric HP (PS) = 735.5 W. 1 BTU/hr = 0.29307 W. So 1000 BTU/hr = 293.07 W. 1 kW = 1.341 HP = 3,412 BTU/hr. For electric motors: 1 HP ≈ 750 W is a common approximation for quick calculations.
Step 2: Power vs Energy
Power (watts, HP) is the rate of energy use. Energy (watt-hours, BTU) is power × time. A 100W light bulb running for 10 hours uses 1,000 watt-hours (1 kWh). Electric bills charge for energy (kWh), not power (kW). If you pay $0.15/kWh and run a 5 kW air conditioner for 8 hours, the cost is 5 × 8 × $0.15 = $6.00.
Step 3: HVAC Tonnage
Air conditioner capacity is rated in tons (of cooling) in the US. 1 ton = 12,000 BTU/hr = 3,517 watts = 4.72 HP. A 3-ton central AC system moves 36,000 BTU/hr of heat. When sizing HVAC, the actual electrical power consumption is lower than the cooling capacity — modern systems have COP (coefficient of performance) of 3-5x.
FAQ
How do I convert watts to horsepower?
Divide watts by 745.7 to get mechanical horsepower. Example: 1000 W / 745.7 = 1.34 HP. Going the other way: multiply HP by 745.7 to get watts. A 5 HP motor = 5 × 745.7 = 3,728.5 watts ≈ 3.73 kW.
What is the difference between mechanical HP and metric PS?
Mechanical (US) horsepower equals 745.7 watts. Metric horsepower (PS or CV, used in Europe) equals 735.5 watts — about 1.4% less. For most purposes the difference is negligible, but specifications from European manufacturers use PS. 100 PS ≈ 98.6 mechanical HP.
How many watts does a typical home appliance use?
A refrigerator: 100-200W. Microwave: 800-1200W. Window AC: 900-1500W. Electric dryer: 4,000-6,000W. Desktop computer: 150-400W. LED light bulb: 8-15W. A typical US home uses about 1.5 kW average power (36 kWh/day), which equals about 2 HP continuously.
What is a BTU/hr?
BTU/hr (British Thermal Units per hour) is used in HVAC to rate heating and cooling capacity. 1 BTU/hr = 0.293 watts. A 'ton' of air conditioning = 12,000 BTU/hr = 3,517 watts. A 2-ton AC unit runs at 7,034 watts (about 9.4 HP) at peak capacity.
Is this power converter free?
Yes, completely free with no signup required. All conversions run instantly in your browser.