Free Online Power Converter: Convert kW, HP, Watts, and More
Converting power units accurately is essential whether you are comparing automotive engine specifications, sizing a solar inverter system, or selecting an air conditioner. Different industries and regions rely on distinct units of measurement—kilowatts are standard in metric regions and electric vehicles, horsepower is widely used in traditional automotive ratings, and BTU per hour dominates HVAC engineering.
Our free Power Converter eliminates manual calculations and rounding errors. It provides instant, high-precision conversions across all major power units.
How to Use the Power Converter
Converting power values takes only a few seconds:
- Select the Starting Unit: Choose your current unit from the From dropdown menu (e.g., kilowatt [kW]).
- Select the Target Unit: Choose the unit you want to convert to from the To dropdown menu (e.g., horsepower [hp, hp (UK)]).
- Enter the Value: Type your numeric value into the Value to Convert input field.
- Calculate: Click the blue Calculate button to view your result instantly.
- Swap or Reset: Click the green swap icon (⇄) to reverse the conversion direction, or click Clear to start fresh.
Understanding Common Power Units
What is Power?
In physics, power is the rate at which energy is generated or consumed over time. In the International System of Units (SI), standard power is expressed in Watts, where 1 Watt = 1 Joule per second.
- Watt (W) & Kilowatt (kW): The foundational SI metric units for electrical and mechanical power. 1 Kilowatt (kW) = 1,000 Watts (W).
- Imperial / Mechanical Horsepower (hp): Originating from James Watt’s experiments with draft horses, this standard is primarily used in the US and UK automotive sectors. 1 hp ≈ 745.7 Watts.
- Metric Horsepower (PS / cv): Commonly used across Continental Europe and Asia in vehicle performance ratings. 1 PS ≈ 735.5 Watts.
- BTU per Hour (BTU/h): British Thermal Units per hour measure heat output and cooling capacity in heating, ventilation, and air conditioning (HVAC) applications.
Power Unit Conversion Quick Reference
The table below shows conversion equivalents starting from a base value of 1 Kilowatt (1 kW):
| Target Unit | Equivalent Value (1 kW) | Direct Formula |
|---|---|---|
| Watt (W) | 1,000 W | kW × 1,000 |
| Imperial Horsepower (hp) | 1.34102 hp | kW × 1.34102 |
| Metric Horsepower (PS) | 1.35962 PS | kW × 1.35962 |
| BTU per Hour (BTU/h) | 3,412.14 BTU/h | kW × 3,412.14 |
| Foot-Pounds per Minute | 44,253.7 ft-lbs/min | kW × 44,253.7 |
| Joules per Second (J/s) | 1,000 J/s | 1 W = 1 J/s |
Core Mathematical Formulas
For manual calculations or software development, use these standard conversion formulas:
- Kilowatts to Mechanical Horsepower:
hp = kW × 1.341022 - Horsepower to Kilowatts:
kW = hp × 0.74569987 - Kilowatts to BTU per Hour:
BTU/h = kW × 3412.142
Real-World Applications
- Automotive Engineering: Compare electric vehicle (EV) motor outputs rated in kilowatts directly against internal combustion engine ratings given in horsepower.
- Renewable Energy & Generators: Size home backup generators, battery storage systems, and solar arrays by calculating total running load in watts or kilowatts.
- HVAC Sizing: Convert air conditioner electrical power consumption (kW) into thermal cooling performance (BTU/h or tons of refrigeration).
Frequently Asked Questions (FAQs)
1. How many Watts are in 1 Horsepower?
One imperial (mechanical) horsepower equals approximately 745.7 Watts. An electrical horsepower, used in electrical motor ratings, is defined as exactly 746 Watts.
2. What is the difference between Imperial HP and Metric HP (PS)?
Imperial HP is defined as 550 foot-pounds per second (≈ 745.7 W). Metric HP (known as Pferdestärke or PS) is defined as 75 kg·m/s (≈ 735.5 W). Imperial HP is roughly 1.4% higher than Metric HP.
3. Why do Electric Vehicles list power output in kW instead of HP?
Kilowatts are the official SI unit for electric power. Since electric motors pull power directly from a battery pack, kW provides an exact, standardized measurement without requiring conversion back to mechanical horse equivalents.
4. How do I convert Kilowatts (kW) to Amps?
To convert kW to Amps, you must know the system voltage (V) and power factor (PF). For a single-phase AC circuit, use the formula:
Amps = (kW × 1000) / (V × PF)
5. What is BTU/h, and how does it relate to Watts?
BTU/h stands for British Thermal Units per hour, measuring the rate of heat energy transfer. One Watt equals approximately 3.41214 BTU/h.
6. Is Boiler Horsepower the same as Mechanical Horsepower?
No. Boiler horsepower (bhp) measures a boiler’s thermal output to evaporate water into steam. One boiler horsepower equals 9,809.5 Watts—nearly 13.15 times greater than standard mechanical horsepower.
7. What is the difference between kW and kWh?
Kilowatt (kW) measures power, which is the rate of energy consumption at a specific moment. Kilowatt-hour (kWh) measures total energy used over time. Running a 1 kW appliance for 1 hour consumes 1 kWh of energy.
8. How many BTU/h equal 1 Ton of Air Conditioning?
One ton of refrigeration capacity equals 12,000 BTU/h, which is equivalent to approximately 3.517 Kilowatts (3,517 Watts).
9. Are these power conversion factors exact?
Conversional prefixes within the metric system (1 kW = 1,000 W) and electrical horsepower (746 W) are exact by definition. Imperial-to-metric conversions rely on international physical standards rounded to high-precision decimals.
10. Does altitude affect power conversion numbers?
The mathematical unit conversion ratio remains identical regardless of location. However, actual physical engines and equipment produce less total horsepower or kilowatts at high altitudes due to lower air density.