What a dollar from any year
is worth today.

What the CPI is, and is not

The Consumer Price Index measures the average change over time in the prices of a fixed kind of shopping: a market basket of the goods and services households buy, from food and rent to cars and doctors’ visits, priced by the Bureau of Labor Statistics every month — about 80,000 prices, it says. The series used here, CPI-U, covers all urban consumers: by the BLS’s description over 90 percent of the U.S. population. It leaves out people in rural nonmetropolitan areas, farm households, military installations and institutions.

It is not your own prices. The basket is the average household’s. If you rent in a city where rents doubled, drive more than most or spend more than most on medicine, your prices moved differently; the BLS’s own words are that the index seldom mirrors a particular consumer’s experience. It is not a complete cost-of-living measure, the BLS says, and it leaves out income and Social Security taxes and investments — shares, bonds, real estate, life insurance. And the further back a comparison reaches, the less the two baskets have in common: a 1913 household bought no air fares, and what a dollar “bought” then is an index figure, not a shopping list.

The series and the base

The calculator and the curve use one series, CUUR0000SA0: all items, U.S. city average, all urban consumers, not seasonally adjusted, monthly from January 1913. Its base is 1982–84 = 100: the BLS sets the average of those thirty-six months to 100, so an index of 300 means prices three times that average. The unadjusted series is used because the BLS calls it final when issued: its CPI-U and CPI-W (the counterpart for urban wage earners and clerical workers) are, the BLS says, commonly used in escalation agreements and to adjust pensions and tax brackets. The seasonally adjusted twin is re-estimated every year and can change for five years, so it is not used here. The thirteen categories are the same kind of series, on the same base; their ids are in the table’s footnote.

Index figures are shown as the BLS publishes them: to one decimal place before 2007 and three from January 2007. That rounding is the BLS’s, and it bounds how exact an early comparison can be — 9.8 in January 1913 stands for anything from 9.75 to 9.85, half a percent either way.

Where the figures come from, and how fresh

The history ships with the page. It was built from the BLS’s own files (download.bls.gov/pub/time.series/cu/) on the day shown under the calculator, each series id checked against the BLS’s catalogue, and it is what the page computes from the moment it opens. Newer months are added live: this site’s server asks the BLS’s public data API (api.bls.gov) one question for all fourteen series and keeps the answer twelve hours for every reader: at most two requests a day while the BLS answers. After a failed read it waits three hours before it asks again, so never more than eight; the API allows an unregistered address 25 requests a day. So a new month can appear here up to twelve hours after the BLS publishes it, later if a read has just failed. When a read fails, the page says so, works from the copy it shipped with and says through which month that copy runs.

Release dates are the BLS’s own, from its schedule page (bls.gov/schedule/news_release/cpi.htm) as read when the page was built. The page shows the next date only while that copy of the schedule holds one; past its last row it says the date is not known here and points to the BLS. A month’s figures come out some two weeks after the month ends, so the newest month here is between about two and six weeks behind the calendar.

Final when issued. The BLS does not revise these series for late data; in the rare case it finds an error it issues a correction. Each live read overlaps the shipped history by a year or more, and if a figure ever differs the page uses the newer one and says which month changed. One month is missing: the BLS published no October 2025 index (its footnote: “Data unavailable due to the 2025 lapse in appropriations”). The page does not fill it in; a calculation or a 12-month rate that needs it says so.

The arithmetic

Equivalent amount = amount × index(to) ÷ index(from). Change in prices = index(to) ÷ index(from) − 1. Average a year = (later index ÷ earlier index) raised to 12 ÷ the number of months between them, minus 1: the steady yearly rate that compounds to the same change. The 12-month rate is the index over the index twelve months earlier, minus 1. A category’s change over five years is its index in the latest month over its index sixty months before. Nothing is estimated, smoothed or forecast.

What this page does not know

• Your own prices, your city’s, or any single shop’s: only the U.S. city average.
• Any month the BLS has not published yet, and October 2025.
• Anything before 1913, or prices in any other country or currency.
• Wages, interest or investment returns: it converts prices, not what money could have earned.
• Where prices are going. It draws no forecast.
• A category in a month the BLS published no figure for it: early years were surveyed quarterly or yearly, and the page says “no figure” rather than interpolate.

Source and terms

Source: U.S. Bureau of Labor Statistics, Consumer Price Index for All Urban Consumers. BLS material is in the public domain; the BLS asks to be cited as the source, and this is that citation. As the BLS’s API terms ask of anyone using it: BLS.gov cannot vouch for the data or analyses derived from these data after the data have been retrieved from BLS.gov. The dates the figures were retrieved are printed under the calculator. This page is not a BLS product and uses no BLS logo. The BLS’s own calculator is at bls.gov/data/inflation_calculator.htm.

What is sent where

Your amount and dates are worked out in your browser and go nowhere. The page asks this site for one file of new months, with no parameters, and this site’s server asks the BLS; the BLS never sees you. A link you copy carries the amount and the two months after a #, the part of an address a browser keeps to itself and does not send to a server; the site’s analytics may record an address as it stands, as the legal page describes. The calculator keeps nothing in your browser; the site remembers only the edition you chose and whether notices are on.

Next door

What money costs rather than what it buys: Rates (the Fed’s range, the Treasury curve, the mortgage; month by month since 1953), Treasury (the public debt and what it pays, inflation-protected securities among it) and Money (the dollar against other currencies).