Inflation Calculator

How the inflation calculator works

Inflation is the general rise in prices over time, which means each dollar buys a little less than it used to. In the US, the standard yardstick is the Consumer Price Index for All Urban Consumers (CPI-U), published monthly by the Bureau of Labor Statistics (BLS). It tracks the price of a fixed basket of goods and services — food, housing, transport, medical care and more — and expresses it as an index where the 1982–84 average equals 100.

To move an amount from one year to another, the calculator multiplies it by the ratio of the two years’ index values. It uses the annual average index for each year (BLS series CUUR0000SA0, not seasonally adjusted), from 1913 — the first year of the index — to 2025, the last complete year. An annual average smooths out month-to-month swings, which suits “what was this worth in 1995?” questions where you don’t know the exact month.

It works in both directions. Converting forward answers “what would my grandparents’ $5,000 salary be today?”; converting backward answers “what would today’s $100 have been in 1970?”.

The second mode, future cost, doesn’t use historical data. It applies a steady inflation rate that you choose to show what today’s prices could become and how much buying power your money could lose — useful for savings goals, salary negotiations and long-term plans such as the retirement calculator.

The formulas

Converting an amount between two years:

Measuring inflation over the period, with CPI₁ the earlier year’s index and CPI₂ the later one, n years apart:

Projecting forward at an assumed rate r for t years:

CPI

annual average Consumer Price Index (CPI-U), 1982–84 = 100

n

number of years between the two dates

r

assumed yearly inflation as a decimal (3% → 0.03)

t

number of years into the future

The average annual rate is a compound (geometric) average: the steady yearly rate that would produce the same total change. It is always lower than a simple average of the yearly percentages when inflation varies.

Worked example: $100 from 2000 in 2025 dollars

1. CPI-U annual average: 172.2 in 2000 and 321.943 in 2025.
2. Price ratio: 321.943 ÷ 172.2 = 1.869588
3. Equivalent amount: $100 × 1.869588 = $186.96
4. Cumulative inflation: 1.869588 − 1 = 86.96%
5. Average yearly inflation over 25 years: 1.869588^(1 ÷ 25) − 1 = 2.53%
6. A dollar in 2025 bought 1 − 1 ÷ 1.869588 = 46.51% less than a dollar in 2000.

In the future-cost mode, $1,000 of spending today becomes $1,343.92 after 10 years at 3% a year (1.03¹⁰ = 1.343916), and $1,000 kept in cash would then buy only what $744.09 buys today.

Reading the result

• It’s an average basket. The CPI-U reflects typical urban household spending. Your own inflation depends on what you buy: rent, tuition or health care can rise much faster than the index, electronics much slower.
• Annual averages differ from month-to-month figures. A December-to-December change and an annual-average change for the same year can differ by a few tenths of a percent. Contracts and benefits often name a specific index and month; use that when the exact figure matters.
• Prices can fall. The index dropped in 1921 and every year from 1930 to 1933, and dipped in 2009. A negative change means a dollar bought more at the later date.
• Compare with what your money earned. Savings or an investment only grew in real terms if they beat inflation over the same years. The compound interest calculator and the investment calculator show nominal growth to set against this.

Limitations of the data

• The index covers the United States only. Other countries publish their own consumer price indexes, and converting between currencies needs exchange rates as well.
• Annual averages before 2007 are published to one decimal place. For the early years, when the index was around 10, that rounding alone can shift a conversion by up to half a percent.
• The October 2025 index was not collected because of the 2025 lapse in federal appropriations; BLS calculated the 2025 annual average from the other eleven months.
• The data ends with 2025, the last complete year. The 2026 annual average will be added when BLS publishes it in early 2027.