I am trying to figure out how to calculate turnaround time in excel.

For example:
Sample 1 - submitted on 01/05/2018 (cell A1)

Test 1 - Completed on 01/07/2018 (Cell B1)
Test 2 - Completed on 01/15/2018 (Cell C1)
Test 3 - Completed on 01/08/2018 (Cell D1)



I want to calculate the overall number of days taken from sample submission date to last test date, however i need the formula to automatically capture the latest date between cells B1 to D1.

=lookup(2,1/(b1:d1=max(b1:d1)),b1:d1)

=MAX(B1, C1, D1)-A1

Excel treats dates as numbers with +1 being an extra day, so this will get you the number of calendar days between submission and the last test. It gets somewhat more complex if you need business days or something, but for calendar days it's really easy.

Thank you Alsadius your formula worked perfectly for what I needed.