Power Converters

One mechanical horsepower is 745.7 watts — so a 100 hp engine puts out about 74.6 kW, and flipping that around, a kilowatt equals 1.341 hp. Those two anchors cover most of what engineers and car buyers actually need, and the kilowatt-to-horsepower converter handles both directions instantly.

Power is the rate at which energy is used or produced — one watt is one joule per second. That single definition connects everything from a phone charger (a few watts) to a grid transformer (hundreds of megawatts), which means the numbers spread across many orders of magnitude. The 11 converters here move cleanly across that range: milliwatts for sensor work, kilowatts for motors and EVs, horsepower for engines, and BTU per hour for HVAC loads. The horsepower-to-watt and watt-to-milliwatt converters are among the most reached-for pairs.

Within the metric side, scale shifts are straightforward powers of ten: a kilowatt is 1,000 watts, a megawatt is 1,000 kilowatts. Horsepower and BTU/hr don't follow that pattern, which is where a converter earns its keep. Start with the popular pairs below, or scroll for the full list.