Hi Bob, thanks for the reply. The tables I use are the max sizes loadable thru the doors of a 747F. On this airplane we have 5 diffent doors, and therefor I have created 5 different tables.

"But you want the user to be able to specify ahead of time whether the value he's entering is a height, width or length, and also whether it's in inches or centimeters. Am I right so far? And you have in mind accomplishing this by creating six different tables and requiring the user to supply two additional values that will determine which of the six tables should be used in the VLOOKUP"

This is exactly what I am trying to achieve. I don't need the operator to see the tables. I only need the result. I.e. if I have a piece H 114 W 20 then L = 458. the user should only see 458