How to index values to 100 from a base year in Excel
Formula (Excel and Google Sheets)
=B2/$B$2*100Divide each value by the locked base value and multiply by 100: =B2/$B$2*100.
- Result on the example
- one result per row in
C2, filled down toC8 - Works in
- Every current version
- Google Sheets
- Same formula
See it work
The formula is already in C2, filled down to C8. Change any input and the result updates, or edit the formula to experiment.
How it works
An index shows every value relative to a base: the base year is 100 and a later value of 142.5 means 42.5% higher than the base. $B$2 is locked so every row divides by the 2019 price. Indexing puts series with different units on one chart, since they all start at 100.
=B2/$B$2*100Result100
B2$3.20The value in B2.
$B$2$3.20The value in B2.
B2/$B$21The / operator divides.
B2/$B$2*100100The * operator multiplies.
In Google Sheets
The same formula works in Google Sheets: =B2/$B$2*100. We ran it in Google Sheets mode on the same data and it returns the same results.
Other ways to do it
Each one was run on the same example sheet.
| Formula | Result | When to use it |
|---|---|---|
| =B2/$B$2-1 | 0.0, 0.0, 0.2…Different result | The change since the base year as a percentage instead of an index. Shows 0.425 (42.5%) for 2025 instead of 142.5. |
Common mistakes
- Without the $, the base moves down with the formula and every row compares with the year before.
- Two indexes can only be compared if they share the same base year.
Try it yourself
Same data, empty answer cell. Your formula is graded instantly, then re-checked on changed data, so a typed-in number won't pass.
Index values to 100 from a base year
C2, turn each year's price into an index where 2019 is 100, then fill down to C8.Questions
How do I change the base year?
Point the locked reference at that year's row, for example =B2/$B$5*100 for 2022.
How do I turn the index back into a percent change between two years?
Divide the indexes: =C8/C5-1 is the change from 2022 to 2025.
Checked by running on 2026-10-30: every formula and result on this page was calculated by the Spreadsheet Practice formula engine, in both Excel and Google Sheets modes.