Worked example: $100 in 2000 to May 2026
The BLS annual average CPI-U for 2000 is 172.2. The latest monthly CPI-U used here is May 2026 at 335.123.
Equivalent amount = $100 x 335.123 / 172.2 = $194.61. The cumulative price-level change is (335.123 / 172.2 - 1) x 100 = 94.6%.
Using the annual-average midpoint for 2000 and the May 2026 month midpoint gives about 25.875 years. The annualized inflation rate is (335.123 / 172.2)^(1 / 25.875) - 1 = 2.6% per year.
How much is money from the past worth today?
Divide the target CPI by the start CPI, then multiply the original amount by that ratio. If the ratio is 2.0, prices are roughly double the start-period level.
How do I calculate cumulative inflation between two years?
Cumulative inflation equals target CPI divided by start CPI, minus 1, then multiplied by 100. This calculator uses annual averages for full-year comparisons.
What is the latest CPI value in this calculator?
The latest embedded monthly value is May 2026 CPI-U at 335.123 from the BLS Public Data API. The latest full-year annual average is 2025 CPI-U at 321.943.
Why does CPI differ from cost of living?
CPI is a national price index. Cost of living can include local housing, taxes, transportation, lifestyle, income, household size, and benefits, so a city-level comparison needs a different dataset.
How to make a shareable inflation result
Use the copy button to share the amount, years, equivalent value, CPI ratio, and a Useful Atlas link. That lets someone else calculate their own amount without needing your exact scenario.