Here is my situation:
I am trying to compare the values I enter (width, height), compare them to a
table and retrieve a value in an associated third column.

So the question is, with these two dimensions (width 4.25, height 2) what
index value will they return? The correct answer is "B" because the width of
4.25 is greater than G5 so it most go to G6 and the height of 2 is smaller
than H6.

Now if the entered width is 8 and the entered height is 10.15 then the
answer would be "C". Because even though the width is equal to G6 the height
is greater than H6, so we have to go up to the next size.

So now to create a formula that can figure this out. Hopefully this makes
sense.

Here is a data sample:
B5(width), C5 (height)
4.25, 2

G5:G8 (widths)
4
8
12
17

H5:H8 (heights)
6
10
12
15.75

I5:I8 (Index)
A
B
C
D

Thanks for your help.