Numarly

Power Converter (All-in-One)

Convert between watts, kilowatts, megawatts, horsepower and BTU/hr instantly

Converted Values

Watt (W): 1.00

Kilowatt (kW): 0.00

Megawatt (MW): 0.00

Horsepower (hp): 0.00

BTU/hour: 3.41

Formula

All conversions are based on Watt (W) as the base unit.

Example: 1 kW = 1000 W

1 hp = 745.7 W

What is it?

This power converter converts between watts, kilowatts, megawatts, horsepower, and BTU per hour simultaneously — widely used in electrical engineering, appliances, and industrial calculations.

Formula

  • 1 kW = 1000 W
  • 1 hp = 745.7 W
  • 1 MW = 1,000,000 W

Formula Explanation

The watt is the SI base unit of power, so kilowatts and megawatts scale it by powers of 10. Horsepower originated as a mechanical unit comparing engine output to a horse's pulling power, while BTU/hour is a thermal power unit common in heating and cooling — both convert to watts via fixed historical factors.

Example Calculation

A car engine rated at 150 hp produces roughly 150 × 745.7 ≈ 111,855 watts (about 111.9 kW).

How to Use

  1. Enter a power value.
  2. Select the unit.
  3. View the converted power across all supported units instantly.

Benefits

  • Bridges electrical (W, kW), mechanical (hp), and thermal (BTU/h) power units.
  • Useful for comparing appliance, engine, and HVAC specifications.
  • Removes the need to memorize multiple conversion constants.

Use Cases

  • Comparing car or engine horsepower to electrical power output.
  • Converting HVAC BTU ratings to watts or kilowatts.
  • Understanding appliance power consumption specs.

What Your Result Means

Each converted value describes the same rate of energy transfer, expressed in a unit suited to its typical domain — watts and kilowatts for electrical devices, horsepower for engines, and BTU/hour for heating and cooling systems.

Tips

  • Use kilowatts for home electricity and appliance ratings.
  • Use horsepower when comparing vehicle or engine specifications.
  • Use BTU/hour for air conditioner and heater capacity comparisons.

Common Mistakes

  • Confusing mechanical horsepower with metric horsepower, which differ slightly (745.7 W vs. 735.5 W).
  • Mixing up kW (power) with kWh (energy over time), which measure different things.
  • Assuming BTU/hour ratings from different manufacturers use identical testing standards.

FAQs

How do I convert kW to horsepower?

Multiply the kilowatt value by 1.341 to get the equivalent in horsepower.

What is a watt?

The watt (W) is the SI unit of power, representing one joule of energy transferred per second.

Why use a power converter?

It helps compare specifications across appliances, engines, and electrical systems that use different power unit standards.

What is the difference between mechanical and metric horsepower?

Mechanical horsepower (745.7 W, used in this converter) and metric horsepower (735.5 W) are slightly different units that both get called "horsepower," which can cause small discrepancies.

Why do air conditioners use BTU/hour?

BTU/hour is a traditional thermal power unit that directly reflects heating or cooling capacity, making it a long-standing standard for HVAC equipment ratings.

How many watts is a typical household appliance?

It varies widely — a phone charger might use 5-20 W, while a space heater can use 1,000-1,500 W, which is why kW is often a more convenient unit for larger appliances.

All conversions are exact based on standard unit definitions.

Last updated: July 25, 2026