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