Horsepower (boiler) to gigawatts conversion calculator above calculates how many gigawatts are in 'X' horsepower (boiler) (where 'X' is the number of horsepower (boiler) to convert to gigawatts). In order to convert a value from horsepower (boiler) to gigawatts (from hp to GW) type the number of hp to be converted to GW and then click on the 'convert' button.