Power unit conversion
Converts power (the rate of energy use) between watts, kilowatts, megawatts, mechanical horsepower, and BTU per hour. This is useful for comparing an appliance's wattage rating against an air-conditioner's BTU rating, or an engine's horsepower against its equivalent kilowatt output.
Why horsepower needs a careful definition
"Horsepower" isn't a single universal unit - mechanical (imperial) horsepower, used in most US and UK engineering contexts, equals about 745.7 watts, while metric horsepower (common in European car specifications) is slightly different at about 735.5 watts. This tool uses the mechanical definition, which matters to flag since the two values are close enough to cause real confusion if the wrong one is assumed.
Why BTU per hour exists alongside watts at all
BTU per hour is a traditional unit for describing heating/cooling capacity, rooted in the historical measurement of heat energy rather than electrical power - it remains the standard way air conditioners and heaters are rated in the US and UK, even though the electrical power they draw is separately measured in watts. Converting between the two lets you directly compare a cooling system's output capacity against its actual electrical draw.
Why results use scientific notation for extreme values
Converting a very large power value (megawatts of industrial output) into a very small unit, or vice versa, can produce numbers that are awkward to read in standard decimal form - the tool automatically switches to scientific notation for extremely large or small results, keeping every conversion readable rather than showing a string of leading or trailing zeros.