Gigawatts to horsepower (mechanical) converter on this page calculates how many horsepower (mechanical) are in 'X' gigawatts (where 'X' is the number of gigawatts to convert to horsepower (mechanical)). In order to convert a value from gigawatts to horsepower (mechanical) (from GW to hp) type the number of GW to be converted to hp and then click on the 'convert' button.