Horsepower-hour to megawatt hours conversion calculator shown above calculates how many megawatt hours are in 'X' horsepower-hour (where 'X' is the number of horsepower-hour to convert to megawatt hours). In order to convert a value from horsepower-hour to megawatt hours (from hph to MWh) simply type the number of hph to be converted to MWh and then click on the 'convert' button.