Wht is the formula to culculate consumers price index

The formula to calculate the Consumer Price Index (CPI) is:

$$\text{CPI} = \frac{\text{Cost of market basket in current period}}{\text{Cost of market basket in base period}} \times 100$$

This formula measures the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services. The base period is a reference period, usually set to 100.