Many people want to interpolate data they have digitized with Dagra in Microsoft Excel. Unfortunately Excel doesn't provide an interpolation function but there is a simple approach.

How do you calculate interpolation?

Know the formula for the linear interpolation process. The formula is y = y1 + ((x - x1) / (x2 - x1)) * (y2 - y1), where x is the known value, y is the unknown value, x1 and y1 are the coordinates that are below the known x value, and x2 and y2 are the coordinates that are above the x value.

Does Vlookup interpolate?

A lookup by itself won't interpolate any data, if an exact match is not wanted, both VLOOKUP and MATCH can return the largest value that is less than or equal to lookup_value. For that kind of match, the column that the functions look in for a match must be sorted.