Kilocalories per day to kilocalories per second conversion calculator shown above calculates how many kilocalories per second are in 'X' kilocalories per day (where 'X' is the number of kilocalories per day to convert to kilocalories per second). In order to convert a value from kilocalories per day to kilocalories per second (from kcal/d to kcal/s) type the number of kcal/d to be converted to kcal/s and then click on the 'convert' button.