I am using the following formale to calculate the aveage number of days used between certain dates. My formula that i am using is =AVERAGEIFS(Mariska!$I$6:$I$5000,Mariska!H6:H5000,">="&C1,Mariska!$H$6:$H$5000,"<="&E1), but i am noti getting and answer. Any other suggestions?