Power Converter

Convert between watts, kilowatts, megawatts, horsepower (mechanical & electrical), BTU/hour, and foot-pounds per second.

Common Power Conversions
FromToResult
1 kWHorsepower (mech)1.34102 hp
1 hp (mech)Watts745.7 W
1 kWBTU/hr3,412.14 BTU/hr
1 MWkW1,000 kW
100 Whp (mech)0.134102 hp
1 GWMW1,000 MW
1 BTU/hrWatts0.293071 W
1 hp (elec)Watts746 W

Frequently Asked Questions

A watt (W) is the SI unit of power, defined as one joule per second (1 J/s). It measures the rate of energy transfer. A 100W light bulb consumes 100 joules per second. The watt is named after James Watt, the engineer who improved the steam engine.

Mechanical (imperial) horsepower = 745.69987 W, defined by James Watt based on a horse's power output. Electrical horsepower = 746 W exactly, used for electric motors. The difference is small (~0.04%) but matters for precise engineering calculations. Car engine ratings use mechanical hp.

One gigawatt = 1,000,000,000 watts (10⁹ W). A typical nuclear power plant generates about 1 GW. The famous "1.21 gigawatts" from Back to the Future is the power needed by the DeLorean's flux capacitor. The total electricity capacity of the US is around 1,200 GW.

BTU/hour is a US unit of power used primarily for heating and cooling equipment — air conditioners, furnaces, and heat pumps are rated in BTU/hr. 1 BTU/hr = 0.293071 W. A typical home air conditioner might be rated at 12,000 BTU/hr (1 "ton" of cooling = 12,000 BTU/hr ≈ 3.52 kW).

One mechanical horsepower = 745.7 watts. A 200 hp car engine produces about 149.1 kW. Electric motors are rated in kilowatts (kW). A 100 kW electric car motor equals about 134 hp. Horsepower is mainly used for vehicles and engines; watts and kilowatts are the SI standard for all other applications.

A kilowatt (kW) = 1,000 watts. A megawatt (MW) = 1,000 kW = 1,000,000 watts. A typical home uses 1–5 kW on average. A large wind turbine generates 2–5 MW. A nuclear power plant generates about 1,000 MW (1 GW). Power plants and grid capacity are measured in MW and GW.

A US home uses on average about 1.2 kW continuously (roughly 900 kWh per month). Peak demand can reach 5–10 kW when running large appliances simultaneously. Common loads: refrigerator (100–200 W), electric dryer (5,000 W), microwave (1,000 W), LED light bulb (10 W), central AC (3,000–5,000 W).

Watt (W) is a unit of power — the rate of energy use at any instant. Watt-hour (Wh) is a unit of energy — power used over time. A 100W bulb running for 10 hours uses 1,000 Wh = 1 kWh. Power is like speed (km/h); energy is like distance (km). You pay for energy (kWh) on electricity bills, not power.

Power is the rate at which energy is transferred or converted, measured in watts (W). Energy is the total amount transferred over time, measured in joules (J) or watt-hours (Wh). Power × Time = Energy. A sports car engine may have high power (500 kW) but a battery stores energy (100 kWh) — these are fundamentally different quantities.

Power factor (PF) is the ratio of real power (watts) to apparent power (volt-amperes, VA) in an AC circuit. A PF of 1.0 means all power is used productively; motors and fluorescent lights often have PF of 0.7–0.9. Utilities may charge industrial customers for low power factor. PF matters only in AC systems, not DC.

About This Power Converter

This free power converter converts between watts, kilowatts, megawatts, horsepower (mechanical and metric), BTU per hour, and other power units. Enter a value in any unit for instant conversions.

When to use this converter

  • Comparing engine power in horsepower vs kilowatts
  • Calculating appliance or server power consumption
  • Converting electrical power ratings between standards

Standards & References

How It Works

Enter Power

Type any power value. The watt (W) is the SI base unit used internally for all conversions.

Choose Units

Select from metric (W/kW/MW/GW), imperial (hp, BTU/hr, ft·lb/s), and electrical horsepower units.

Get Result

Instant conversion with the exact factor used. Swap units and reference the table for quick comparisons.

Common Use Cases

Engine & Vehicle Power

Convert car engine ratings between horsepower and kilowatts to compare vehicles across US and European specifications.

HVAC & Home Appliances

Convert air conditioner and heater ratings between BTU/hr and kW for international comparisons and energy consumption calculations.

Solar & Renewable

Convert solar panel output and wind turbine capacity between W, kW, and MW for energy system design and comparison.

Electronics & Computing

Understand power supply ratings, processor TDP, and device consumption between watts and kilowatts for system design and billing.

Industrial Machinery

Convert motor and pump power ratings between horsepower and kW for procurement, motor selection, and international engineering specs.

Physics Education

Verify power unit conversions for mechanics problems, thermodynamics assignments, and engineering exam preparation.

Related Converters

Energy Converter
Pressure Converter
Speed Converter
Temperature Converter

Related Articles

View all articles
1000VA Isn't 1000W: Power Factor and Why UPS Sizing Often Goes Wrong

1000VA Isn't 1000W: Power Factor and Why UPS Sizing Often Goes Wrong

A UPS rated "1000VA" and a power supply rated "1000W" sound like the same quantity — they're not. VA (apparent power) and W (real power) differ by the power factor, and many common devices have power factors well below 1.0, meaning a "1000VA" UPS often can't actually support 1000W of real load. Here's what power factor means, why UPS units are rated in VA in the first place, why "naive" sizing (treating VA and W as interchangeable) can leave far less headroom than expected, and how active PFC closes the gap in modern equipment.

Jun 15, 2026
Human Power Output in Sport: FTP, W/kg, How Power Meters Work, and What 400 Watts Means

Human Power Output in Sport: FTP, W/kg, How Power Meters Work, and What 400 Watts Means

Professional cyclists sustain 400+ watts — and W/kg (watts per kilogram) determines who wins on climbs. Here's FTP and power training zones, how cycling power meters work, human power output in different sports, and why mechanical efficiency means 250W of cycling burns 850 kcal/hour metabolically.

Jun 10, 2026
Renewable Energy Power Output: Capacity Factors, What "Homes Powered" Really Means, and Grid Balancing

Renewable Energy Power Output: Capacity Factors, What "Homes Powered" Really Means, and Grid Balancing

A 500 MW wind farm doesn't deliver 500 MW continuously — its 40% capacity factor means average output closer to 200 MW. Here's how capacity factors compare across energy sources, what "homes powered" claims actually mean, how grids balance intermittent renewables, and solar panel output calculations.

Jun 10, 2026
Power Explained: Watts vs kWh, Appliance Running Costs, and Why Data Centres Matter

Power Explained: Watts vs kWh, Appliance Running Costs, and Why Data Centres Matter

Power is the rate of energy use — the difference between kW and kWh explains your electricity bill. Here's how to calculate running costs for any device, data centre PUE and why AI training is energy-intensive, and EV charger power levels compared.

Jun 9, 2026
Power Converter — Watts, kW, Horsepower & BTU/hr Explained

Power Converter — Watts, kW, Horsepower & BTU/hr Explained

Learn how power units like watts, kilowatts, horsepower, BTU/hr, and tonnes of refrigeration relate to each other — with real examples for generators, AC units, car engines, and solar panels.

Jun 6, 2026