The Explainer Desk
The story behind the story.

Inflation calculator

A dollar in 1970 and a dollar today are not the same amount of money. The standard way to compare them is the Consumer Price Index, the government’s monthly measure of what a broad basket of goods and services costs. Pick a year and an amount and this calculator scales it by the change in that index — no forecasts, no assumptions, just the published data. It measures prices in general, not any one price.

How the math works

  • Value today = your amount × (latest index ÷ the start year’s index). Both numbers come from the Consumer Price Index for All Urban Consumers (CPI-U): U.S. city average, all items, not seasonally adjusted, with 1982–84 = 100.
  • The start year uses its annual average — the mean of that year’s monthly indexes, which is how the Bureau of Labor Statistics publishes a year. “Today” is a single month: the latest published index, September 2026 = 336.940 (BLS series CUUR0000SA0). Comparing a yearly average with one month is the usual convention for this kind of calculator; it also means results shift a little each month as new data comes out.
  • The 2025 annual average (321.943) covers 11 months, not 12: BLS published no October 2025 index because the data were not collected during the lapse in federal appropriations that fall.
  • “Average per year” is the steady yearly rate that would turn the start-year average into the latest index, counting from the middle of the start year to the latest month.
  • The CPI tracks what urban consumers as a group pay for a broad basket. Your own inflation depends on what you buy and where you live — How the Consumer Price Index is actually measured explains what the index does and doesn’t capture.

This is general information about price statistics, not financial advice. Editorial standards.

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