Power Converter - Free Online Tool

Convert power units instantly. Support for 5+ units including Watt, Kilowatt, Megawatt. Free calculator with accurate conversions, formula, and table.

🔋 Power Converter

Select your units from the lists below

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From Unit

Watt
Symbol: W

Kilowatt
Symbol: kW

Megawatt
Symbol: MW

Horsepower
Symbol: hp

BTU per Hour
Symbol: BTU/h

To Unit

Watt
Symbol: W

Kilowatt
Symbol: kW

Megawatt
Symbol: MW

Horsepower
Symbol: hp

BTU per Hour
Symbol: BTU/h

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🔋 Power Converter

Power measurements appear in electrical engineering, mechanical systems, and energy management. Convert between watts, kilowatts, horsepower, and other power units instantly. Whether you're designing electrical systems, evaluating engine performance, or managing energy consumption, our converter handles the calculations.

🔋 About Power

Power measures the rate at which work is done or energy is transferred—how quickly energy is used or produced. In the International System of Units (SI), power is measured in watts (W), defined as one joule per second. From electrical engineering and mechanical systems to energy management, power measurements are used across many fields. Different industries use different units. The metric system (watts, kilowatts, megawatts) dominates global science and most countries, while horsepower remains common for describing engine and motor output, especially in automotive applications. Working with all these units helps with engineering design, equipment specification, and energy efficiency analysis.

Understanding Power Measurement

Power is a derived physical quantity representing the rate at which work is done or energy is transferred. In the International System of Units (SI), power is measured in watts (W), defined as one joule per second (1 W = 1 J/s), or equivalently, one newton-meter per second. The watt is named after James Watt, whose improvements to the steam engine were central to the Industrial Revolution. Since power is derived from energy (joule) and time (second), and both are based on fundamental constants, the watt inherits precision and reproducibility. Power can be calculated as the product of force and velocity for mechanical systems, or as the product of voltage and current for electrical systems. The relationship between power, energy, and time is fundamental: energy equals power multiplied by time.

📜 History & Context

The history of power measurement dates back to the Industrial Revolution, when engineers needed to compare the output of steam engines to the work done by horses. In the late 1700s, James Watt observed horses working in breweries and estimated that a horse could perform about 33,000 foot-pounds of work per minute. He defined this as one "horsepower" to help market his steam engines, giving potential customers a familiar reference point for comparing machines to animals. The modern unit of power, the watt, was proposed in 1882 by C. William Siemens in honor of James Watt. Initially defined in terms of electrical units (one ampere times one volt), the watt was adopted at the Second International Electrical Congress in 1889. In 1948, the 9th General Conference on Weights and Measures redefined the watt in absolute terms as one joule per second, making it a coherent SI derived unit. This definition was formalized with the adoption of the International System of Units (SI) in 1960. As the base units (kilogram, meter, second) were redefined using fundamental constants in 2019, the watt gained the same precision and universality. Today, power measurement benefits from precise standards maintained by institutions like NIST and coordinated by BIPM, ensuring consistent and reproducible measurements worldwide.

✨ Fun Facts

• Horsepower was invented by James Watt as a marketing tool to help sell steam engines, based on his observation that a horse could perform about 33,000 foot-pounds of work per minute.
• One horsepower equals approximately 745.7 watts, though actual horses can produce much more power in short bursts—up to about 15 horsepower during peak exertion.
• The watt is named after James Watt, but he didn't invent the unit—it was proposed in 1882, over 60 years after his death, to honor his contributions to steam engine development.
• A 100-watt light bulb consumes 100 joules of energy every second it operates, demonstrating the direct relationship between power (watts) and energy consumption over time.
• The number 5,252 appears in the formula relating torque and rotational speed to horsepower—this constant comes from the original definition of horsepower and unit conversions.

💡 Real-World Examples

• Electrical systems: Appliances and devices are rated in watts or kilowatts. Converting between units helps with energy consumption calculations, circuit design, and international equipment compatibility.
• Automotive engineering: Engine power is specified in horsepower or kilowatts depending on the market. Converting between units helps with international vehicle comparisons and emissions standards.
• Renewable energy: Solar panels and wind turbines generate power measured in watts or kilowatts. Converting between units helps with system sizing, grid integration, and energy production reporting.
• Industrial motors: Electric motors are rated in horsepower or kilowatts depending on region. Converting between units helps with equipment selection, efficiency analysis, and international standards.
• Household appliances: Power consumption is measured in watts. Converting to kilowatts helps calculate electricity costs and understand energy usage.
• Power generation: Power plants produce electricity measured in megawatts or gigawatts. Converting between units helps with grid capacity planning and international energy reporting.
• Electronics and computing: Computer processors and electronic devices consume power measured in watts or milliwatts. Converting between units helps with battery life calculations and thermal management.
• Mechanical systems: Hydraulic and pneumatic systems measure power in horsepower or kilowatts. Converting between units helps with system design and efficiency optimization.

🔧 Common Applications

• Electrical engineering: Circuit design, power system analysis, and energy management need accurate power measurements. Converting between units helps with system design and efficiency optimization.
• Automotive and transportation: Engine power ratings, electric vehicle specifications, and fuel efficiency calculations use various power units. Converting between units helps with international standards.
• Energy generation and distribution: Power plants, renewable energy systems, and electrical grids measure power in different units. Converting between units helps with capacity planning and grid management.
• Industrial automation: Motor sizing, process control, and equipment specification need power measurements. Converting between units helps with optimal system design and energy efficiency.
• Consumer electronics: Device power consumption, battery capacity, and energy efficiency ratings use various power units. Converting between units helps with product comparison and energy cost calculation.

❓ Frequently Asked Questions

+ How do I convert watts to horsepower?

To convert watts to horsepower, divide the watt value by 745.7 (for mechanical horsepower) or 735.5 (for metric horsepower). For example, 1,000 watts equals approximately 1.34 mechanical horsepower or 1.36 metric horsepower. Horsepower is commonly used for engine power ratings.

+ What is the difference between watts and kilowatts?

A watt is the base unit of power in the SI system, while a kilowatt equals 1,000 watts. For example, 1 kilowatt equals 1,000 watts, and 5 kilowatts equals 5,000 watts. Kilowatts are commonly used for larger power measurements like electrical systems and engines.

+ How do I convert horsepower to kilowatts?

To convert horsepower to kilowatts, multiply the horsepower value by 0.7457 (for mechanical horsepower) or 0.7355 (for metric horsepower). For example, 100 horsepower equals approximately 74.57 kilowatts (mechanical) or 73.55 kilowatts (metric).

+ What is a watt and how is it defined?

A watt is the SI unit of power, defined as one joule per second. It represents the rate at which energy is transferred or work is done. For example, a 100-watt light bulb consumes 100 joules of energy per second, and a 1,000-watt appliance consumes 1 kilowatt of power.

+ How do I convert BTUs per hour to watts?

To convert BTUs per hour to watts, multiply the BTU/h value by 0.293071. For example, 1,000 BTU/h equals approximately 293 watts, and 10,000 BTU/h equals approximately 2,930 watts. This conversion is useful for HVAC systems and heating equipment.