The following Microsoft Excel formula performs linear interpolation by
calculating the interpolation step value
is the cell address of the larger number, and start
is the cell address of the smaller number.
is a method used to determine a present or future value factor when the exact factor does not appear in either a present or future value table. Interpolation assumes that the change between two values is linear and that the margin of error is insignificant.
To create a sample linear interpolation formula, follow these steps:
- Type the following values in a worksheet:
A1: 9 B1: =(A7-A1)/(ROW(A7)-ROW(A1))
- Select cells A2:A6. On the Edit menu, point to Fill, and then click Down. The formula is filled down, and the following values are displayed in cells A2:A6:
: You must type the reference to the step value in cell B1 as an absolute reference (with dollar signs).