HI i have 2 columns of data which is created date and resolved date both formatted as dd-mm-yyyy-h:mm the MTTR column is formatted as dd:hh:mm and the formula used is =(NETWORKDAYS(R146,S146)-1)*("17:00"-"8:00")+IF(NETWORKDAYS(S146,S146),MEDIAN(MOD(S146,1),"17:00","8:00"),"17:00")-MEDIAN(NETWORKDAYS(R146,R146)*MOD(R146,1),"17:00","8:00") the calculation made does not seem to provide an accurate MTTR in days hours mins. See example attatched, I also have a yes/no formula based on specific time values if the MTTR cell is less than or greater than say 10 minutes or xx hours. again cant seem to get itworking correctly. any help greatly appreciated.