Power Unit Converter - Convert Watts, Horsepower, BTU/hour & More
Power Converter
Quick Conversions
Top Power Units
Watt (W)
The SI derived unit of power
Kilowatt (kW)
1,000 watts - common for household appliances
Horsepower (hp)
Mechanical power output, especially in vehicles
BTU per hour (BTU/h)
Used for heating and cooling systems
Megawatt (MW)
1,000,000 watts - used for large power plants
Ton of refrigeration
Used in commercial air conditioning
All Power Units (A-Z)
Top Power Conversions
What is Power?
Power is the rate at which energy is transferred or converted. In physics, it's defined as the amount of work done per unit of time. The SI unit of power is the watt (W), which equals one joule per second. Power measurements are essential in engineering, physics, and everyday life, from determining the energy consumption of household appliances to calculating the output of industrial machinery.
Understanding power units and conversions is crucial for various applications. Engineers need to convert between watts and horsepower when designing mechanical systems, HVAC technicians convert BTU per hour to watts when sizing heating and cooling equipment, and electricians convert kilowatts to watts when calculating electrical loads.
For example, a 100-watt light bulb consumes energy at a rate of 100 joules per second. A car engine might produce 200 horsepower, which is equivalent to about 149,140 watts. A large commercial air conditioner might have a cooling capacity of 5 tons of refrigeration, which equals 60,000 BTU per hour or about 17,584 watts.
Common Use Cases
Electrical Engineering
Calculating power consumption of devices, sizing electrical systems. For example, converting 1.5 kW to 1,500 W for circuit breaker selection.
Mechanical Engineering
Engine output ratings, motor specifications. For example, converting 150 hp to 111,853 W for performance calculations.
HVAC Systems
Heating and cooling capacity ratings. For example, converting 3 tons of refrigeration to 36,000 BTU/h for system sizing.
Renewable Energy
Solar panel output, wind turbine capacity. For example, converting 5 MW to 5,000 kW for grid integration planning.
Historical Evolution of Power Measurement
The concept of power has evolved alongside our understanding of work and energy. The watt, named after James Watt, was adopted as a unit of power in the 19th century to measure steam engine output. Horsepower was defined earlier by James Watt himself to compare steam engine power to that of draft horses. The BTU (British Thermal Unit) per hour became standard for heating and cooling systems.
Today, power measurements span from microwatts in electronic circuits to gigawatts in large power plants. The International System of Units (SI) standardizes power measurement with the watt as the base unit, enabling our power converter to handle both everyday and specialized applications.
Frequently Asked Questions
What is the standard unit of power?
The watt (W) is the SI derived unit of power, defined as one joule per second. This makes it the foundation for all metric system conversions and power measurements worldwide. As the base SI unit for power measurement, the watt ensures consistency in scientific research, engineering projects, and international trade.
How do I convert between watts and horsepower?
Use standard conversion factors: 1 horsepower (metric) = 735.5 watts, 1 horsepower (mechanical) = 745.7 watts. Our power converter tool handles these conversions automatically with high precision, eliminating calculation errors and saving time for students, engineers, and professionals.
What's the difference between mechanical and metric horsepower?
Mechanical horsepower (also called imperial horsepower) is defined as exactly 745.7 watts, while metric horsepower is defined as exactly 735.5 watts. This small difference originated from different definitions of the pound and foot in the imperial and metric systems. Our power converter handles both types accurately.
Why are there so many units of power?
Different units serve different contexts and industries. Watts for electrical power, horsepower for mechanical systems, BTU/hour for heating and cooling, and tons of refrigeration for large HVAC systems. This variety allows for convenient expression of power measurements across all applications, from small electronics to large industrial systems.
How accurate are your power conversions?
Our power converter uses internationally recognized conversion factors and mathematical formulas for maximum accuracy. All calculations are performed with high-precision arithmetic to ensure reliable results for both simple everyday conversions and complex engineering measurements requiring extreme accuracy.
Can I convert between any power units?
Yes, our comprehensive power converter supports conversions between all common units including watts, kilowatts, megawatts, horsepower (metric and mechanical), BTU per hour, and tons of refrigeration. Whether you need to convert 1 watt to horsepower or 1 megawatt to BTU/hour, our tool handles all common units.
What industries use power conversion most?
Power conversion is essential across numerous industries including electrical engineering (circuit design), mechanical engineering (engine ratings), HVAC (system sizing), renewable energy (solar/wind capacity), automotive (engine performance), and manufacturing (equipment power requirements). Engineers and technicians in these fields rely on accurate power conversions daily.
Is your tool free to use?
Yes, our power converter is completely free to use with no registration required. Simply enter your value, select your units, and get instant, accurate results. We believe accurate measurement conversion should be accessible to everyone, from students doing homework to professionals working on complex engineering projects.