Power Converter

1. Enter the value you want to convert.
2. Choose the from unit.
3. Choose the to unit.
4. Read the result and the conversion rate.

Here is what each result means:

Power is the rate at which energy is used or work is done. A powerful engine or heater does more work each second than a weak one. Because power appears in engineering, motoring and heating, it is measured in several units, and a figure can arrive in watts, kilowatts, horsepower or BTU per hour depending on where it comes from.

The SI unit is the watt, one joule of energy per second. Larger amounts use kilowatts and megawatts: a kettle is about 2 kilowatts, and a power station is measured in megawatts. Cars traditionally use horsepower, a unit dating from the age of steam, and heating and cooling equipment is often rated in BTU per hour.

This converter bridges every unit through the watt. It multiplies your value by the watts in its unit, then divides by the watts in the target unit. Because each unit has a fixed value in watts, the conversions are exact and never change.

One point to watch is that horsepower comes in more than one flavour. Mechanical horsepower, common in the United States and Britain, is about 745.7 watts, while metric horsepower, often written PS, is about 735.5 watts. This converter offers both, so a car rated in one can be compared with a figure in the other.

It converts through the watt, the SI unit of power.

1. Your value is multiplied by its unit's value in watts.
2. That gives the power in watts, the common base.
3. Dividing by the target unit's value in watts gives the result.

For the physics side, see the power calculator and the energy converter.

Convert 1 horsepower to watts.

Result: 1 mechanical horsepower is about 745.7 watts, or 0.746 kilowatts. The metric horsepower is a little less, about 735.5 watts, which is why the two figures differ slightly.

Every unit has a fixed value in watts.

Kilowatts and megawatts scale the watt for large machines and power plants. Horsepower survives from the steam age as the popular unit for engines, and BTU per hour is the standard rating for air conditioners and heaters.

The two horsepower units are close but not identical.

The two differ by about 1.4 percent, so a car quoted as 200 PS is a little less powerful than 200 mechanical horsepower. When comparing engine figures across regions, it is worth checking which horsepower is meant.

The Two Units

The ratio between the from-unit and to-unit sets the result; each has a fixed value in watts.

Which Horsepower

Mechanical and metric horsepower differ slightly, so choose the right one.

Power vs Energy

Power is a rate; a kilowatt is not the same as a kilowatt-hour, which is energy.

Motoring

Convert an engine's power between horsepower and kilowatts.

Heating and Cooling

Read an air conditioner rated in BTU per hour in watts.

Engineering

Move between watts and other units in calculations.

1. Mixing Horsepower Types

Mechanical and metric horsepower differ by about 1.4 percent. Check which is meant.

2. Confusing Power and Energy

A kilowatt is power; a kilowatt-hour is energy. They are different quantities.

3. Mixing BTU with BTU per Hour

A BTU is energy; BTU per hour is power. This converter uses BTU per hour.

4. Wrong Direction

Check which unit is the from and which is the to; swapping them inverts the result.

5. Rounding Too Early

Convert first, then round, so small differences do not build up.

Conversions use fixed factors relative to the watt.

About 745.7 watts for mechanical horsepower, or 0.746 kilowatts. Metric horsepower (PS) is a little less, about 735.5 watts.

Multiply mechanical horsepower by 0.7457. So 200 horsepower is about 149 kilowatts. This converter does it in both directions.

The watt, one joule per second. Larger amounts use kilowatts and megawatts, and horsepower is a traditional unit for engines.

Mechanical horsepower is about 745.7 watts and is used in the US and UK. Metric horsepower, or PS, is about 735.5 watts and is used in Europe and Japan.

Multiply BTU per hour by about 0.293. So a 12,000 BTU per hour air conditioner is about 3,517 watts of cooling power.

No. A kilowatt is power, the rate of using energy. A kilowatt-hour is energy, a kilowatt sustained for one hour.

PS stands for Pferdestaerke, the German for horsepower. It is metric horsepower, about 735.5 watts, common in European car specifications.

It survives from the steam age as a familiar way to describe engine power. Many countries now quote kilowatts too, so converting is often useful.

No. The calculation runs in your browser and nothing you enter is stored or sent anywhere, unless you choose Save, which keeps the result only on this device.

• Watt (Wikipedia).
• Horsepower (Wikipedia).
• Power (physics) (Wikipedia).