Calories per day to horsepower (metric) conversion calculator above calculates how many horsepower (metric) are in 'X' calories per day (where 'X' is the number of calories per day to convert to horsepower (metric)). In order to convert a value from calories per day to horsepower (metric) (from cal/d to hp) simply type the number of cal/d to be converted to hp and then click on the 'convert' button.