Inflation Calculator

How the inflation calculator works

Inflation means prices rise, so the same dollar buys less over time. To compare money from two different dates, the calculator scales the amount by how much the consumer price index changed between them. If the index doubled, you need twice the dollars for the same buying power.

An example with real numbers: the CPI-U averaged 172.2 in 2000 and stood at 334.980 in August 2026. So $100 from 2000 equals 100 × 334.980 ÷ 172.2 = $194.53 in August 2026. Prices rose 94.5% in total, which works out to 2.58% a year on average.

Reverse mode runs the same formula the other way: it divides by the later index and multiplies by the earlier one. It answers questions like “what would something that costs $100 today have cost in 1990?” With the latest data the answer is $39.02.

The average yearly rate is a smoothed figure. It is the steady rate that would take prices from the first index to the second over the time in between. Real inflation is bumpy: some years are far above the average, a few years even had falling prices. The calculator counts the time from the middle of one date to the middle of the other, so from one full year to another it is simply the difference of the years.

What the CPI is

The Consumer Price Index is published by the U.S. Bureau of Labor Statistics (BLS). BLS defines it as a measure of the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services. Its data collectors record the prices of about 80,000 items each month, grouped into food and beverages, housing, apparel, transportation, medical care, recreation, education and communication, and other goods and services.

This calculator uses the CPI for All Urban Consumers (CPI-U), U.S. city average, all items, not seasonally adjusted. That is BLS series CUUR0000SA0, the same series the official BLS CPI Inflation Calculator uses. According to BLS, the CPI-U population makes up over 90 percent of the U.S. population. The index has a reference base of 1982-84 = 100, so a value of 300 means prices are three times their 1982-84 level. BLS says the CPI-U is final when issued, so past values are not revised later.

A dollar then and now

What $1 from each year buys in August 2026, and how much of its buying power the dollar has lost since then:

Buying power lost is the share a dollar has lost since that year. At 90%, a dollar today buys only a tenth of what it bought then. A salary works the same way. Someone who earned $50,000 in 2015 needed about $67,916 in 2025 just to keep the same buying power, a raise of 35.8% that only kept pace with prices.

Full years or single months

Each date can be a full year or a single month. “Full year” uses the annual average index that BLS publishes for that year, which smooths out moves within the year. BLS notes that annual averages tend to be less volatile than changes from one December to the next. A month uses the index for that month only. The official BLS CPI Inflation Calculator works with months, so to check a result against it, pick a month on both dates. We tested this calculator against the BLS calculator for several pairs of months, and the results match to the cent.

Two gaps are worth knowing about. The current year, 2026, has no annual average yet, so it offers months up to August, the latest month BLS has published. And October 2025 has no index at all: BLS could not collect price data that month because of the 2025 lapse in appropriations. BLS still published an annual average for 2025.

What the CPI cannot tell you

The CPI is a good yardstick for the general price level, but it has limits that matter for how you read the result:

• It is an average. BLS states that the CPI does not necessarily measure your own experience with price change. A renter in an expensive city, a retiree with high medical bills and a family with a long commute all see different inflation.
• It covers urban consumers. People in rural areas outside metro areas, in farm households, on military installations and in institutions such as prisons are not part of the CPI-U population.
• It is not a full cost-of-living index. BLS points out that the CPI is often called one but differs from a complete cost-of-living measure in important ways.
• Some costs are left out. The CPI includes sales and excise taxes tied to prices, but not income or Social Security taxes, and not investment items such as stocks, bonds, real estate and life insurance. It does not tell you how home prices or the stock market changed.
• Other indexes exist. BLS also publishes the CPI-W for wage earners and clerical workers, a subset of about 30 percent of the population, and the chained CPI (C-CPI-U), which allows for substitution across item categories. BLS notes that the CPI-U and CPI-W are commonly used to adjust contracts, pensions and tax brackets, so check which index applies to yours.

Tips for using inflation-adjusted numbers

• To see whether a raise beat inflation, enter your old salary with the year you earned it and compare the result with your new salary.
• Old prices in books, news stories and family records make more sense in today’s dollars. Enter the price and its year, keep the latest month as the second date.
• For long spans, look at the average per year as well as the total. A total of several hundred percent over several decades can still be a moderate yearly rate.
• Rounding matters a little: BLS index values before 2007 have one decimal, so results for older dates carry a small rounding margin.

How to use the inflation calculator

1. 1Choose what to calculate: what an amount from the past is worth later, or what a later price would have cost back then.
2. 2Enter the amount in US dollars, then pick the two dates. Each one can be a full year or a single month.
3. 3Read the amount with the same buying power, the total and average yearly inflation, the chart of buying power over time and the table with other years. Copy the result, share a link or download all years as CSV.

Frequently asked questions