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