CPI Inflation Calculator
Inflation is the slow repricing of everything, and the Consumer Price Index is its official ruler. Enter an amount of money, the CPI in its year and the CPI in the year you are comparing with, and this CPI inflation calculator converts the amount between the years — and reports the true average inflation rate across the span, the number that makes “a dollar isn’t what it was” into arithmetic.
What the CPI Actually Measures
The Consumer Price Index, published monthly by the US Bureau of Labor Statistics, tracks the price of a fixed basket of goods and services — food, housing, transport, medical care, apparel and the rest — weighted by what urban households actually spend. The index is anchored so that the 1982-84 average equals 100; every value since is that basket's price relative to the anchor. The conversion this page performs is the index's intended use: equivalent amount = amount x (CPI in the target year) / (CPI in the source year). Two disciplines keep the arithmetic honest. Use the same series throughout (CPI-U, the headline index, is this page's assumption; the BLS also publishes CPI-W and chained variants). And prefer annual averages for year comparisons — a single month's index carries seasonal noise that the average irons out. The official source is the Bureau of Labor Statistics CPI pages, where every figure in the table below can be checked.
Worked Example: $100 of 2010, Priced in 2024
The defaults: the US CPI-U annual average was 218.056 in 2010 and 313.689 in 2024. So $100 in 2010 money equals 100 x 313.689 / 218.056 = $143.86 in 2024 money — the same basket costs 43.86 percent more. Across the 14 years, the average annual inflation rate is (313.689/218.056)^(1/14) − 1 = 2.63 percent per year. Run it backwards for the sentence everyone actually wants: $100 today buys what $69.52 bought in 2010 (100 x 218.056/313.689). The reference table for the calculator's inputs — CPI-U annual averages: 2000: 172.2 · 2005: 195.3 · 2010: 218.056 · 2015: 237.017 · 2020: 258.811 · 2024: 313.689. With those six numbers you can price any amount across a quarter-century: a $30,000 salary in 2000 is the equal of about $54,600 in 2024 (30,000 x 313.689/172.2), and a $50,000 house in 1970 (CPI 38.8) matches roughly $404,000 today — the arithmetic behind every "in my day" conversation, settled.
Average Inflation Is a Geometric Fact
The average rate this calculator reports is deliberately not the total divided by the years (43.86/14 = 3.13 percent — too high). Inflation compounds: each year's increase applies to the already-increased level, so the true average is the constant rate that, compounded, lands on the same total — the geometric mean, (end/start)^(1/years) − 1. The distinction matters wherever inflation is quoted: the Federal Reserve's 2 percent target is a compounded rate, long contracts escalate geometrically, and the handy rule of 72 (years for prices to double ≈ 72 divided by the rate) is the geometric fact wearing a shortcut — at 2.63 percent, prices double in about 27 years, which is precisely the 2010 basket's story told forward.
Where CPI Conversions Are Used
The formula prices more of ordinary life than its name suggests. Contracts and alimony/child-support orders escalate by CPI so payments keep real value. Social Security and tax brackets are indexed by statute (the tax code uses a chained CPI variant; benefits use CPI-W). Wage negotiations and "real" salary comparisons — whether a raise beat inflation is this division, not a feeling: a 3 percent raise in a 4 percent year is a real pay cut of about 1 percent. Historical prices — what a 1960 house, a 1985 car or a 2000 salary "would be today" — are CPI conversions, with the caveat that the basket itself changes: no CPI can price a smartphone into 1970, which is why very long comparisons are honest approximations, not exact ones. And savings goals: a retirement target set in today's money needs this page's forward run — at 2.63 percent, $1,000,000 of spending power 25 years out requires about $1,915,000 of nominal money, a number that rearranges savings plans on first meeting.
Deflation, Disinflation and the Vocabulary of the Index
The CPI also disciplines three words that headlines blur. Deflation is the index falling — prices lower than a year ago, a negative inflation rate; the US has seen it only briefly since the 1930s (2009's annual average dipped to 214.537 from 215.303, a genuine if mild deflation year, and those two values in this calculator convert $100 of 2008 into $99.64 of 2009). Disinflation is the index rising more slowly — inflation falling from 9 percent to 3 percent while prices still climb; most "inflation is coming down" headlines describe disinflation, and a household budget feels no relief in levels, only in the speed of the climb. Stagflation is the index rising briskly while the economy stagnates — the 1970s combination (CPI 38.8 in 1970 to 82.4 in 1980, prices more than doubling in a decade, an average of 7.8 percent a year) that permanently changed how central banks rank their fears. The calculator handles all three without opinion: ratios below 1 are deflation, ratios above 1 with a smaller rate than the prior span are disinflation, and the geometric average reports either with the same indifference. Knowing which regime you are in matters because the right response differs — deflation rewards holding cash and punishes debtors (debts grow in real terms), disinflation rewards patience, stagflation rewards real assets and fixed-rate borrowing — and the index, read properly, tells you the regime before the editorials do.
Which CPI Should You Enter? A Short Buyer's Guide
The defaults use annual averages because most questions are year-shaped — "what was a 2010 salary worth in 2024?" — and averages silence seasonal noise. Three situations call for different entries. For a specific purchase or contract date, use the monthly CPI for those two months (the BLS publishes the not-seasonally-adjusted CPI-U monthly; it is the series contracts cite). For Social Security-flavoured questions, CPI-W is the statutory index — its values run close to CPI-U but not identical, and the calculator takes either. For very recent conversions, remember the index publishes with a lag of a few weeks and is never revised in its headline form (annual averages are final), so "today's CPI" always means "the latest published month's" — close enough for every purpose outside a courtroom. When in doubt, run both the average-based and the month-based conversion: the gap between them is the honest error bar on the answer, and reporting the range is better scholarship than a falsely precise point.
Related Tools
More from the Finance Calculators hub: the Discounted Cash Flow Calculator — inflation's mirror image, pricing future money in today's — the Interest Rate Calculator, and the SIP Calculator for growing money faster than prices.
Frequently Asked Questions
What is the current US CPI?
The CPI-U annual average for 2024 was 313.689, up 2.9 percent on 2023 — the figure this page's defaults use as the later year. Monthly values through 2025 run higher still (the index is published monthly, around the middle of the following month). For a comparison "to today", enter the most recent annual average for stability, or the latest monthly CPI from the BLS release for the freshest conversion; the calculator accepts any pair of values from any years.
Why does my personal inflation feel different?
Because your basket is not the national basket: a renter in a fast-rising city, a family with three children in childcare, or a retiree heavy in medical spending each lives a different weighted average than the CPI-U household. Economists call these "inflation inequality", and the BLS publishes demographic experimental indexes showing spreads of a percentage point or more between groups. The CPI remains the right ruler for contracts and comparisons; for your household's truth, weight the categories by your own spending — the formula is the same, the basket yours.
What is the difference between CPI-U, CPI-W and chained CPI?
Coverage and construction: CPI-U covers all urban consumers (about 93 percent of the population) and is the headline; CPI-W covers urban wage-earners and clerical workers (about 29 percent) and drives Social Security adjustments; chained CPI (C-CPI-U) accounts for consumers substituting cheaper goods when prices rise, which trims it by roughly 0.25 points a year, and it is the version the US tax code has used since 2018. Conversions over long spans differ slightly by series — pick one and stay with it, as this page's note insists.
How far back does CPI data go?
The modern CPI-U series begins in 1913 (index value 9.9), with reconstructed estimates reaching into the 19th century from historical price research. A dollar of 1913 equals roughly $31-32 of 2024 money by the index — the century's cumulative repricing, and the reason long-held cash is a wasting asset. For pre-1913 conversions, academic series (such as the ones MeasuringWorth maintains) extend the ladder, with widening error bars the further back it climbs.
Is CPI the same as the inflation rate the Fed targets?
Not quite: the Federal Reserve targets 2 percent on the PCE price index (personal consumption expenditures, from the Bureau of Economic Analysis), which weights medical care and housing differently and usually runs a few tenths below CPI. News reports quote CPI because it is older, monthly and contractual everywhere; policy is set by PCE. This calculator is a CPI instrument — contracts, escalations and "what was it worth" questions are CPI territory — and the distinction is worth knowing precisely so headlines stop confusing the two.