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Inflation Calculator

What an amount of money is worth in another year, using the official CPI series.

Enter an amount and two years between 1913 and 2025.

What do you want to work out?

1913 onwards

Up to 2025

Exact calculation. Given your inputs, this is the answer — no estimation involved.

How this calculator works

Historical mode uses the official CPI-U annual averages published by the Bureau of Labor Statistics — the Consumer Price Index for All Urban Consumers, U.S. city average, all items. The conversion is the ratio of the two years’ index values, which is the standard method BLS itself documents.

Annual averages are used rather than a specific month, so results are stable and reproducible. A January-to-January comparison and a December-to-December one give different answers, and neither is "the" inflation rate for a year.

The implied annual rate is the geometric mean over the period, not a simple average — because inflation compounds.

Projection mode applies a rate you choose going forward, because nobody has future CPI data. It is clearly labelled as an assumption rather than a measurement.

The formula

Exactly what happens to your numbers, step by step.

  1. Converting between years

    value in year B = amount × (CPI in B ÷ CPI in A)

  2. The implied annual rate

    rate = (CPI_B ÷ CPI_A)^(1 ÷ years) − 1

    A geometric mean, because inflation compounds year on year.

  3. Projecting forward

    future amount = amount × (1 + assumed rate)^years

A worked example

What $100 in 2000 is worth in 2020.

What you enter

Amount
$100
From year
2000
To year
2020

The working

CPI-U in 2000
172.2
CPI-U in 2020
258.811
Ratio
1.5029
Adjusted amount
$150.29
Annualised rate
2.06% a year

$100 in 2000 has the buying power of $150.29 in 2020

Prices rose 50% over those twenty years. Put the other way, a dollar from 2000 bought about 67 cents’ worth of goods by 2020.

Assumptions

Every result here rests on these. Change your inputs and the result changes with them.

  • CPI-U annual averages, the official series for U.S. urban consumers.
  • The index measures a national basket of goods and services, weighted to average urban spending.
  • Projection mode uses a rate you choose, not measured data.

What this cannot tell you

  • **CPI is a national average and will not match your experience.** Your personal inflation rate depends on what you actually buy — housing, healthcare and education have risen much faster than the overall index.
  • It does not capture regional cost-of-living differences.
  • Comparisons across very long spans are weaker than they look. The basket of goods in 1913 bears little resemblance to today’s, so the arithmetic is exact but the comparison is loose.

Questions people ask

What is CPI?

The Consumer Price Index, a measure of the average change in prices paid by urban consumers for a basket of goods and services. CPI-U is the version covering all urban consumers, and it is the series used here.

Why does this not match my own experience of prices?

Because CPI tracks an average national basket. If your spending is weighted towards housing, healthcare or education — all of which have outpaced the index — your personal inflation rate is higher than the headline number.

How do I calculate inflation between two years myself?

Divide the later year’s CPI by the earlier year’s and multiply by your amount. That ratio is the whole calculation; everything else here is presentation.

What rate should I assume for the future?

The Federal Reserve targets 2% over the long run, and 2% to 3% is a common planning assumption. It is an assumption either way — actual inflation has ranged from negative to double digits within living memory.

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Sources and review

Sources

Methodology version 1.0.0 · Last reviewed