What this calculator does
Find out what money from one year is worth in another year's dollars. For example, enter $1,000 from 2000, and see what it would take in 2025 to buy the same things. The calculator uses the official US Consumer Price Index (CPI-U), a measure of everyday prices, averaged for each year from 1913 to 2025. It shows how much prices rose in total, the average rise per year and a year-by-year table.
It also works forward. Pick a rate-based option to see what something costing a given amount today will cost later. Or see what a future sum will be worth in today's money. Both use an average inflation rate you choose. That's the right tool for planning, because nobody knows what future prices will be.
Where it's used
Why this math matters outside the classroom:
- Historical prices. Writers convert a price from decades ago into today's dollars by multiplying it by the ratio of the two years' price index values.
- Future costs. At 3% a year, something that costs $100 today would cost about $134.39 in 10 years.
- Comparing wages. Workers compare a raise with the change in prices over the same period to see whether pay kept up.
- History lessons. Students restate prices from old newspapers in today's dollars to compare the cost of living across eras.
Grade level and standards: Grades 7–9; Common Core State Standards for Mathematics 7.RP.A.3, HSF.LE.A.1.c. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose what you want to know. The first option uses real US price data to compare two past years. The other two use a steady rate you enter.
- Enter the amount. For the price-data option, enter the year the amount is from and the year you want it in. Either year can be the earlier one.
- For a rate option, enter the average yearly inflation rate and the number of years instead.
- Read the converted amount. Then open the table to see the price index and the matching amount for every year in between.
What the inputs mean
- Amount is in dollars of the year
- The year your dollars come from, such as the year a price was paid or a salary was earned. Any year from 1913 to 2025.
- Convert to dollars of the year
- The year you want the answer in. Usually that's the latest year (2025). It can also be earlier than the start year, to turn today's money into an older year's dollars.
- Average annual inflation rate
- Your own guess at an average yearly rate, not a forecast. Over the long run, US inflation has averaged a few percent a year. Choose the rate that fits your plan.
- Years
- Any number of years above zero. Part years use the same formula.
Formula and method
value in year B = amount × CPI(B) ÷ CPI(A) cumulative inflation = CPI(B) ÷ CPI(A) − 1 average yearly inflation = (CPI(later) ÷ CPI(earlier))^(1 ÷ years) − 1 future cost = amount × (1 + r)^t value in today's money = amount ÷ (1 + r)^t
In the formulas, A is the year your money comes from and B is the year you want it in. CPI(A) and CPI(B) are the yearly average index values for those two years. The index tracks the average price of the same basket of everyday goods and services. So dividing one year's value by the other shows how much prices changed between them.
The average yearly rate is the one steady rate that would give the same total change over those years. Each year's rise builds on the last, so the formula takes a root (the power 1 ÷ years) instead of just dividing by the number of years.
In the rate options, r is the yearly inflation rate as a decimal (3% is 0.03) and t is the number of years. Prices rise once a year, each time on top of the last rise. So after t years, prices are (1 + r)^t times today's.
Worked example
You want to know what $1,000 in 2000 is worth in 2025 dollars.
- CPI-U annual averages: 172.2 for 2000 and 321.943 for 2025.
- Price-level ratio: 321.943 ÷ 172.2 ≈ 1.86958769.
- Value in 2025 dollars: $1,000 × 1.86958769 ≈ $1,869.59.
- Cumulative inflation: about 86.96%. Spread over 25 years, that is an average of about 2.53% a year.
- A dollar held from 2000 to 2025 lost about 46.51% of its buying power.
Result: $1,000 in 2000 had about the same buying power as $1,869.59 in 2025.
Understanding the result
The converted amount tells you what something would cost in the other year's money, for a typical mix of household purchases. Say you earned $1,000 a month in 2000. If your pay had grown to less than $1,869.59 a month by 2025, it fell behind prices.
The average yearly rate smooths out the ups and downs. The table shows the real rate for each year. You'll spot jumps such as 1980 and 2022, and the falling prices of the early 1930s.
In the rate options, purchasing power lost is how much less a fixed sum can buy. Savings that earn less than the inflation rate lose buying power, even while the balance grows.
Assumptions and limitations
- The price-data option uses the CPI-U for the US city average, all items, not seasonally adjusted, as yearly averages. Prices within a year are averaged, so January and December amounts are treated the same.
- The rate options assume one steady rate, with prices rising once a year.
- Nothing is rounded during the math. The published index values are used exactly as released.
- The price data covers 1913 to 2025. The 2026 average isn't out until the year is over. This page will be updated when it is.
- The Bureau of Labor Statistics (BLS) didn't collect October 2025 price data, because federal funding lapsed in 2025. The 2025 figure here is the yearly average BLS published.
- The CPI-U reflects what people in cities spend, on average. Your own costs can rise faster or slower. Items such as housing, tuition or medical care often rise at a different pace from the overall index.
- Nobody knows future inflation, so the rate options are what-if estimates. Rates must be between −50% and 100% a year.
Frequently asked questions
How much is $100 from 1970 worth today?
Using yearly averages, $100 in 1970 (CPI 38.8) is about $829.75 in 2025 dollars (CPI 321.943). Enter any amount and any two years to get your own figure.
Why use annual averages instead of a single month?
Yearly averages smooth out seasonal swings, and they're the standard way to compare whole years. If you need one exact month, the monthly index from BLS will give a slightly different answer.
What is the CPI-U?
It's the Consumer Price Index for All Urban Consumers, the most quoted US inflation measure. The Bureau of Labor Statistics publishes it every month. It tracks prices for a broad basket of goods and services that households in cities buy, and cities hold most of the population. The index is set so that 1982–84 = 100.
Why is 10 years at 3% more than 30%?
Each year's rise is added to prices that have already gone up. After 10 years at 3%, prices are 1.03^10, or about 1.344 times today's. That's a 34.39% rise.
How long does it take for prices to double?
A handy rule of thumb is 72 divided by the rate in percent. At 3%, that's about 24 years. In real CPI numbers, prices roughly doubled between 1990 (130.7) and 2021 (270.970).
Can I convert today's money into an older year's dollars?
Yes. Put the later year in the first year box and the earlier year in the second. For example, $100 in 2025 is about $40.60 in 1990 dollars.
Does this account for wages or investment returns?
No. It measures household prices only. To see whether your pay or savings kept up, compare their growth with the total price rise for the same years.
Sources
- U.S. Bureau of Labor Statistics: CPI for All Urban Consumers (CPI-U), U.S. city average, all items (series CUUR0000SA0) (checked 2026-10-18)
How this calculator is checked
Method: Price-index ratio CPI(B) ÷ CPI(A) using BLS CPI-U annual averages (series CUUR0000SA0, retrieved 2026-10-18); constant-rate compounding (1 + r)^t for projections. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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