Calories per second to kilocalories per day converter on this page calculates how many kilocalories per day are in 'X' calories per second (where 'X' is the number of calories per second to convert to kilocalories per day). In order to convert a value from calories per second to kilocalories per day (from cal/s to kcal/d) type the number of cal/s to be converted to kcal/d and then click on the 'convert' button.