AJ Designer

Power Unit Converter

Result equals value times the ratio of conversion factors

Power Conversion =

1 Watt (W)

Solution in Other Units

UnitValue
Watt (W)1
Kilowatt (kW)0.001
Megawatt (MW)1e-6
Horsepower (hp)0.0013410221
Foot-Pound / Second (ft·lbf/s)0.73756215
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How It Works

This converter uses the watt (W) as its base unit — the SI unit of power equal to one joule per second. Each power unit has a known factor relative to the watt. The converter multiplies your input value by the source unit’s watt-equivalent factor, then divides by the target unit’s factor, using BigNumber for full precision.

Example Problem

Convert 5 horsepower (hp) to watts (W).

  1. 1 horsepower = 745.7 watts.
  2. 5 × 745.7 = 3,728.5 W.

Key Concepts

Power measures the rate of energy transfer, with the watt (1 J/s) as the SI base unit. Common units include kilowatts (electrical appliances), horsepower (engines and motors), and BTU/hour (HVAC systems). Conversions are simple multiplications because each unit has a fixed ratio to the watt.

Applications

  • Electrical engineering: converting between watts, kilowatts, and horsepower for motor specifications
  • HVAC design: translating between BTU/hour and kilowatts when sizing heating and cooling equipment
  • Automotive engineering: comparing engine output across horsepower, kilowatt, and PS (metric horsepower) ratings
  • Energy auditing: converting power measurements between imperial and metric units for international reporting

Common Mistakes

  • Confusing mechanical and electrical horsepower — mechanical HP is 745.7 W, electrical HP is 746 W, and boiler HP is 9,810 W; always verify which definition applies
  • Mixing up power (watts) and energy (watt-hours) — power is a rate, energy is power multiplied by time; 1 kW running for 2 hours is 2 kWh of energy
  • Using metric horsepower (PS) interchangeably with mechanical horsepower — 1 PS = 735.5 W vs 1 HP = 745.7 W, a 1.4% difference that compounds in large motors

Frequently Asked Questions

How many watts are in one horsepower?

One mechanical horsepower equals approximately 745.7 watts (or about 0.7457 kW). This is the most common definition, based on James Watt’s original comparison of steam engines to draft horses.

What is the difference between a watt and a kilowatt?

A kilowatt (kW) is simply 1,000 watts. Kilowatts are commonly used for household appliances and electricity billing. For example, a typical microwave oven uses about 1 kW, and electricity is billed in kilowatt-hours (kWh).

What is foot-pound per second?

A foot-pound per second (ft·lbf/s) is an imperial unit of power equal to approximately 1.356 watts. It represents the power needed to move one pound-force through one foot in one second. One horsepower equals 550 ft·lbf/s.

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