CPI Calculator

Convert a dollar amount between two periods using Consumer Price Index values. Enter an amount and the start and end CPI, then press Calculate.

Written by TopicDrill Editorial Team·Updated June 2026

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How the CPI calculator works

The Consumer Price Index tracks the average price of a fixed basket of goods and services over time. To compare money across two periods, you scale the amount by the ratio of the two index values. If prices have risen, the adjusted amount is larger, which reflects the loss of buying power that inflation causes.

The math is Adjusted = Amount times the end CPI divided by the start CPI. The same ratio minus one, expressed as a percentage, gives the total inflation between the periods.

A quick example

Suppose the start period CPI is 100 and the end period CPI is 130. A $1,000 amount becomes 1,000 times 130 divided by 100, which is $1,300. Prices rose 30 percent, so you would need $1,300 to buy what $1,000 bought before.

Things to keep in mind

CPI measures average prices, so your personal inflation can differ depending on what you buy. For official index values and methodology, see the U.S. Bureau of Labor Statistics. You can also explore our other free calculators.

Frequently asked questions

What is the Consumer Price Index?

The Consumer Price Index, or CPI, measures the average change over time in the prices households pay for a basket of goods and services. A rising CPI means prices are going up, which is inflation. It is published by national statistics agencies such as the U.S. Bureau of Labor Statistics.

How does this CPI calculator work?

It multiplies your amount by the ratio of the end period CPI to the start period CPI. The formula is Adjusted = Amount times (end CPI divided by start CPI). This restates the value in the prices of the end period.

Where do I find CPI index values?

Official CPI index numbers are published monthly and annually by government statistics offices. In the United States the Bureau of Labor Statistics provides historical CPI data you can look up for any month or year.

What does the adjusted amount tell me?

It shows how much money you would need in the end period to have the same buying power as the original amount in the start period. The total inflation figure is the cumulative price increase between the two periods.

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