Inflation Calculator
This CPI inflation calculator has three modes. Historical (CPI) takes an amount, a start year and an end year. It shows what the amount is worth in the end year's dollars, the cumulative inflation between the two years and the average annual rate. The end year can come before the start year. The data is the annual average Consumer Price Index for All Urban Consumers (CPI-U) that the US Bureau of Labor Statistics publishes, for every year from 1913 to 2025. Future cost and past value use one rate you enter for every year instead. Future cost grows today's amount by that rate and shows what the same things will cost at the end. Past value runs the other way. Both show the share of buying power the money loses.
How to use the Inflation Calculator
- Enter your numbers in the Inflation Calculator above.
- Press the Calculate button to see the result.
- To try other numbers, change any value and press the button again.
The inflation formulas
Historical: Value = A × CPI(end) ÷ CPI(start) · · · Future cost = A × (1 + i)^n · · · Past value = A ÷ (1 + i)^n · · · Loss = 1 − 1 ÷ (1 + i)^n
A is the amount you enter. In Historical (CPI) mode, CPI(start) and CPI(end) are the CPI-U annual averages for the two years, BLS series CUUR0000SA0, with 1982-84 = 100. Cumulative inflation is the later year's CPI divided by the earlier year's, minus 1. The average annual rate is the yearly rate that compounds to the same change over the years between them. In the other two modes, i is the annual inflation rate as a decimal (3% is 0.03) and n is the number of years. The rate stays the same every year. For whole years that is the rate compounded once a year. A part year is the same power with a fraction in it: 2.5 years at 3% multiplies the amount by 1.03^2.5, about 1.0767, so $1,000 becomes $1,076.70. The loss is the share of its buying power a fixed sum of money gives up over the n years. Money figures are rounded to the cent.
Worked example
In Historical (CPI) mode, $100 from 1980 is worth $390.71 in 2025 dollars. The CPI-U annual average was 82.4 in 1980 and 321.943 in 2025, and 100 × 321.943 ÷ 82.4 = 390.71. Prices rose 290.71% over those 45 years, an average of 3.07% a year. With a fixed rate of 3% a year for 10 years, future cost mode turns $1,000 into 1,000 × 1.03^10 = $1,343.92. Past value mode turns $1,000 at the end of those 10 years into $744.09 at the start. In both cases the money loses 25.59% of its purchasing power.
Frequently asked questions
How much is $100 from 1980 worth today?
$390.71 in 2025 dollars. 2025 is the last full year of CPI data in the calculator. Choose Historical (CPI) and enter 100, 1980 and 2025. The calculator multiplies 100 by the 2025 CPI-U annual average of 321.943 and divides by the 1980 average of 82.4. The figures come from the Bureau of Labor Statistics, series CUUR0000SA0: all items, U.S. city average, all urban consumers, not seasonally adjusted. The calculator compares whole years, so it has no monthly values.
Which inflation rate should I enter?
In Future cost and Past value, enter the rate you expect for the years ahead, or one you want to test. For the US, the Bureau of Labor Statistics publishes the Consumer Price Index (CPI) and its percentage change over the last 12 months. Enter that change if you want to carry the latest rate forward. Historical (CPI) needs no rate, because it reads the change from the CPI table.
What does purchasing power loss mean?
It is the share of what your money can buy that inflation takes away over the period. At 3% for 10 years, prices end up 1.3439 times as high, so a fixed $1,000 buys what $744.09 bought at the start, a loss of 25.59%. The figure depends only on the rate and the years, so Future cost and Past value show the same loss for the same inputs.