Index Number Calculator — Formula
## How to Calculate an Index Number
### Formula
**Index = (Current Value / Base Value) * Base Index**
An index number expresses a value relative to a base period. The base period is typically set to 100. An index of 125 means a 25% increase from the base. Index numbers are used for price indices (CPI), stock indices, and economic indicators.
### Formula
**Index = (Current Value / Base Value) * Base Index**
An index number expresses a value relative to a base period. The base period is typically set to 100. An index of 125 means a 25% increase from the base. Index numbers are used for price indices (CPI), stock indices, and economic indicators.
Esempio Risolto
A commodity priced at $125 today vs. $100 in the base year.
- Index = (125 / 100) * 100 = 125
- Change from base = ((125/100) - 1) * 100 = 25%
- The price is 25% above the base period.