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