Power is the rate at which energy is used, produced, or transferred — measured in watts, where one watt equals one joule of energy per second.

How many watts are in one horsepower?

One mechanical horsepower equals about 745.7 watts. Metric horsepower (PS) is slightly smaller, at about 735.5 watts.

What's the difference between mechanical horsepower and metric horsepower (PS)?

Mechanical horsepower (745.7 W) is the traditional imperial unit used in the US and UK. Metric horsepower, also called PS or CV, is slightly smaller at 735.5 W and is commonly used in continental Europe and Japan for vehicle ratings.

How do I convert kW to hp?

Divide the kW value by about 0.7457 (or multiply by about 1.341) to get mechanical horsepower.

How do I calculate power from voltage and current?

Multiply voltage by current: P = V × I. For example, 230 V × 5 A = 1,150 W. This applies directly to DC and resistive AC loads; real AC circuits may also involve a power factor.

How do I calculate how many kWh a device uses?

Multiply the device's power in kilowatts by the number of hours it runs: Energy (kWh) = Power (kW) × Time (h). The "Energy from Power" calculator on this page does this automatically, in any power unit.

How do I calculate electricity cost?

Work out the energy used in kWh, then multiply by your electricity price per kWh: Cost = kWh × Price. The "Electricity Cost" calculator on this page does both steps at once.

What is a BTU per hour?

A British Thermal Unit per hour (BTU/h) measures the rate of heat transfer, commonly used to rate air conditioners, heaters and furnaces. One BTU/h is about 0.293 watts.

What is a ton of refrigeration?

A ton of refrigeration is a cooling-power unit equal to 12,000 BTU/h, based on the rate needed to melt one ton of ice in 24 hours. It's about 3,517 watts, and commonly used to size air conditioning systems.

How is power related to torque?

For rotating machinery, power equals torque multiplied by angular velocity: P = T × (2π × RPM ÷ 60). The same torque produces more power at a higher rotational speed.

How is power related to energy?

Power is the rate of energy use, while energy is the total amount used over time: Energy = Power × Time. A 1,000-watt device running for 1 hour uses 1,000 watt-hours (1 kWh) of energy.

Is this power converter free to use?

Yes, it is completely free, requires no registration, and runs entirely in your browser with no usage limits.

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Power Conversions

9 units · 4 calculators

Power Converter & Calculator

Convert watts, kilowatts, megawatts, horsepower, BTU/h and more, then work out electrical power from voltage and current, energy used over time, electricity cost, or motor efficiency — all calculated instantly in your browser.

9Power units

4Calculators

0msServer round-trips

Result / power-field unit

1150W

P = V × I = 230 V × 5 A = 1150 W

From

hp

To

kW

74.5699872kW

kW = hp × 0.7456999

Runs locally, no data sent Standard NIST/BIPM factors Free, no sign-up

How each calculation works

The formula behind each calculator above, with a short note on when you'd use it.

Quick conversion table

Common values for your selected units in the converter above, updated automatically.

hp	kW

Power unit reference

What each unit means, where it's used, and how it relates to the watt.

More converters from ConvertGPT

Power is closely tied to energy and torque — these are the ones people pair with it most often.

Frequently asked questions

Straight answers to the questions people ask most about power units and calculations.

All calculations and conversions run locally in your browser using standard NIST/BIPM conversion factors. No data is sent anywhere.

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