Inflation Calculator: How to Adjust Money for Inflation
An inflation calculator converts a dollar amount from one year into the equivalent amount in another year, using the Consumer Price Index (CPI). A $100 bill from 1990, for example, had the buying power of about $246 in 2025.
How the Conversion Works
In the US the standard measure is the CPI for All Urban Consumers (CPI-U), published monthly by the Bureau of Labor Statistics. The conversion is a ratio of index values:
Value in year B = Amount in year A × (CPI in year B ÷ CPI in year A)
Example: the CPI-U annual average was 82.4 in 1980 and 321.943 in 2025. So $1,000 in 1980 equals $1,000 × 321.943 ÷ 82.4 ≈ $3,907 in 2025 dollars. Put the other way, a dollar kept as cash since 1980 lost about three-quarters of its buying power. The Inflation Rate calculator takes two CPI values and returns the percentage change between them; here (321.943 − 82.4) ÷ 82.4 × 100 ≈ 290.7%.
Adjusting for inflation matters whenever you compare money across years: investment returns, salaries from different decades, or retirement spending decades from now. A $50,000 salary in 1990 bought far more than $50,000 does today.
How Inflation Erodes Purchasing Power
Inflation is the general rise in prices, which means each dollar buys less over time. The Federal Reserve targets 2% annual inflation, but even low rates add up over decades.
Example: a car that cost $15,000 in 1995 (CPI-U 152.4) corresponds to about $31,700 in 2025 dollars. Over the long run, CPI-U has risen a little over 3% a year on average since 1913, with large swings between decades.
Because inflation compounds, 3% a year halves purchasing power in about 23 years (2% a year takes about 35). Savings earning less than the inflation rate lose real value even while the nominal balance grows, which is why long-term investors look at returns after inflation. The Inflation Impact calculator projects either the future cost of today's amount or today's purchasing power of a future amount from an assumed annual rate and number of years.
Money's Changing Value Through the Decades
The 1970s saw several years of double-digit inflation. Using annual averages, a 1970 dollar (CPI-U 38.8) needed about $8.30 in 2025 to buy the same things, an increase in the price level of roughly 730%.
The CPI is an average across a basket of goods, and individual categories move at different speeds. To check whether something has outpaced general inflation, adjust its old price and compare the result with what it costs today. For example, $3,000 of tuition in 1980 is about $11,700 in 2025 dollars; if the same program now costs much more than that, its price has risen faster than the CPI.
Inflation calculators compare one currency across time. To compare what money buys in different countries at the same time, see purchasing power parity explained instead.
Using the Calculators
For an exact conversion you need the CPI-U value for the starting date and the ending date, both published by the BLS, whose own CPI Inflation Calculator covers 1913 onward. Enter the two values in the Inflation Rate calculator to get the percentage change, then multiply your amount by (1 + that change) for the equivalent value.
Example: a $5,000 salary in 1950 (CPI-U 24.1) works out to about $66,800 in 2025 dollars, which gives context to historical wage comparisons.
The calculation also runs backward: $100,000 in 2025 corresponds to about $40,600 in 1990 dollars (CPI-U 130.7). Annual averages and single-month figures give slightly different answers, so use the same convention for both years.
If you only know an average inflation rate rather than index values, the Historical Inflation calculator compounds an amount from a start year to an end year at that rate; it is an approximation, since actual inflation varied year by year.
Related guides: purchasing power parity explained and the present value calculator for what future money is worth today.