What are the main units used for measuring power?

The main power measurement units are: 1) Watt (W) - SI unit of power, 2) Horsepower (hp) - mechanical/electrical power, 3) Kilowatt (kW) - larger power measurements, 4) BTU/hour - heating/cooling power, 5) Megawatt (MW) - industrial scale power, 6) VA (volt-amperes) - apparent power in AC systems.

How do you convert between watts and horsepower?

To convert between watts and horsepower: 1) 1 horsepower = 745.7 watts, 2) 1 kilowatt = 1.341 horsepower, 3) For quick estimates: 750W ≈ 1 hp, 4) For mechanical horsepower: 1 hp = 550 ft⋅lbf/s, 5) For metric horsepower: 1 PS = 735.5 watts, 6) Electric motor ratings often use hp in US/UK.

What is the difference between power and energy?

Power and energy differences include: 1) Power is rate of energy use (watts), 2) Energy is total power over time (watt-hours), 3) Power × Time = Energy (e.g., 1000W × 1 hour = 1kWh), 4) Power is instantaneous, energy is cumulative, 5) Utility bills measure energy (kWh), not power.

How do you calculate electrical power?

Calculate electrical power using: 1) DC power: P = V × I (voltage × current), 2) AC power: P = V × I × PF (power factor), 3) Three-phase power: P = √3 × V × I × PF, 4) Resistive power: P = I²R, 5) Apparent power: VA = V × I, 6) Real power: W = VA × power factor.

Power Unit Info

Common power units:

Watt (W): SI unit of power
Kilowatt (kW): 1,000 watts
Horsepower (hp): 745.7 watts
BTU/hour: heating/cooling power
Volt-ampere (VA): apparent power

Key relationships:

1 hp = 745.7 W = 0.7457 kW
1 kW = 1.341 hp = 3,412.14 BTU/h
1 BTU/h = 0.2931 W = 0.0003931 hp

Origins of Power Units:

The watt (W) was introduced in the late 18th century, named after James Watt, the Scottish engineer who significantly improved the steam engine. It was officially adopted as the SI unit of power in 1960.

Horsepower Development:

Horsepower was defined by James Watt in the 1780s to compare steam engine output to draft horses. Several standards developed: mechanical/imperial horsepower (745.7 W), metric horsepower/PS (735.5 W), and electrical horsepower (746 W).

Thermal Units:

The British Thermal Unit (BTU) emerged in the late 19th century from heating applications. BTU per hour became standard for HVAC system ratings and remains widely used, especially in the United States.

Watts are used for:

Household electronics and lighting
Small electrical devices
Solar panel output ratings
Computer component power consumption

Horsepower is used for:

Vehicle engines (especially in US/UK)
Industrial motors and engines
Pumps and compressors
Lawn equipment and power tools

Other units:

BTU/hour: HVAC systems, heaters
kW and MW: electrical utilities
VA and kVA: electrical equipment rating
W/m²: solar radiation, heat flux

Power Conversion Calculator

From:

To:

Conversion Result

1 BTU/h=

1.000 GW

Use the converter above to calculate different values and units

What are Power Measurements?

Power measurements quantify the rate at which energy is transferred, used, or transformed. The fundamental unit of power is the watt (W), defined as one joule of energy per second (J/s). Power is a crucial measurement in electrical, mechanical, thermal, and many other engineering and scientific applications.

Different power units evolved to suit various industries and applications. While watts and kilowatts are standard in electrical applications, horsepower remains common for engines and motors, BTU per hour for heating and cooling systems, and watt per square meter for radiation intensity measurements.

Common Power Conversions

Power conversions are essential in electrical engineering, mechanical systems, HVAC, renewable energy, and industrial applications. They enable precise calculations across different power measurement systems and are fundamental to understanding energy transfer rates, efficiency, and system performance.

Practical Applications of Power Conversions

Educational Resource

This educational video explains how to convert between different power units including watts, horsepower, and kilowatts.

Power Conversion Resources

Download Power Conversion Chart (PDF)

Get our comprehensive power conversion chart showing relationships between watts, horsepower, kilowatts, BTUs, and other power units for quick reference in engineering calculations and everyday applications.

Related Conversion Tools:

Power Conversion FAQs

Find answers to common questions about power measurements and conversions.