Table Lookup (two-dimensional) with Interpolation

[monsterlucifer]

Hello,

I have this table which I wrote by getting values from a graph (included in the image below).

I am able to get the exact values as far as they match the values in X and Y axis using the INDEX and MATCH functions.

What I am trying to achieve is to get interpolated values for the X and Y axis. For instance, for Ns=2500 and gpm=2500, the percentage from graph is 84% approximately. How can I do this using functions in excel.

Any help would be much appreciated. Screenshot of the worksheet is below and here is also a link to the file as well.

 

[C Moore]

I guess you would have to interpolate for both gpm and Ns then average them.

 

[monsterlucifer]

Yeah figured it out with someone's assistance.