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