Is Consumer Price Index (CPI) and Inflation the same thing?

Consumer Price Index (CPI) and Inflation are often confused with each other but they are not the same thing.

Consumer Price Index (CPI)

It is an index number that gives us a general idea about the price level in a country. This index number is made using prices of a specific number of goods that a typical consumer in a country would use. This index is calculated using weight of each good according to its importance. such indexes are usually made with a base year. CPI is Stock  calculated for many purposes and that includes inflation.

Inflation.

Inflation is an overall increase in the price level of a country. Mathematically Inflation is the percentage change in CPI over a period of time. If suppose CPI in 2015 is 100 and CPI in 2016 is 110 then inflation for the year is 10 percent.

you can explain the difference of CPI and Inflation as Stock vs Flow concept.

Some points worth noting

1. CPI is not the only index used for calculating price level. there are other indexes which serves the same purpose but with a little bit of variations. Wholesale Price Index (WPI) for example is also an index measuring price level but using prices of wholesale products.

2. Inflation can be calculated WPI and GDP deflator as well.