How the result is calculated
Money is not a fixed unit of value. The same note bought less in 2024 than in 2000, and far less than in 1980, and the only honest way to compare sums from different years is through the prices of the things they bought. This guide explains the index that makes that possible for fifteen countries, works two examples through, and sets out what a national average can and cannot tell you.
Adjusted amountAmount × Index(to) ÷ Index(from)
Cumulative inflationIndex(to) ÷ Index(from) − 1
Average annual rate(Index(to) ÷ Index(from))1 ÷ years − 1
Purchasing powerAmount × Index(from) ÷ Index(to)
- Index(y)
- the annual average of the country's consumer price index for year y
- years
- the number of years between the two dates
The average annual rate is a compound (geometric) figure: the single rate that, applied every year, would produce the same total change. It is a little lower than simply averaging each year's inflation rate, because compounding does part of the work.
Worked example
| Item | Amount | How it is obtained |
|---|---|---|
| Index for 2000 | 172.2 | CPI-U annual average, 1982-84 = 100 |
| Index for 2025 | 321.943 | CPI-U annual average |
| Ratio | 1.8696 | 321.943 ÷ 172.2 |
| Adjusted amount | $186.96 | 100 × 1.8696 |
| Cumulative inflation | 87% | 1.8696 − 1 |
| Average annual rate | 2.53% | 1.86961 ÷ 25 − 1 |
| Purchasing power of $100 of 2000 money in 2025 | $53.49 | 100 × 172.2 ÷ 321.943 |
Switch the country to the United Kingdom and the same arithmetic runs on the ONS index: £100 of 2000 money is £184.15 in 2024, a rise of 84% at 2.58% a year.
| Country | 2024 value | Average annual rate |
|---|---|---|
| United States | $205.86 | 2.52% a year |
| United Kingdom | £199.24 | 2.41% a year |
| Germany | €168.15 | 1.81% a year |
| Japan | ¥113.14 | 0.43% a year |
Japan is the outlier: nearly three decades in which prices barely moved. The same saved yen kept almost all of its value, which no amount of arithmetic on American or British inflation would have told you.
Reading the result
The headline is the adjusted amount: what the sum you entered is worth in the money of the later year. Beneath it are the cumulative rise, the average annual rate and the buying power of the original amount, and a derivation that quotes the two index levels and the series they came from.
An index only means something against its own base period. Most of the series here are set to 100 in 2010, so an index of 150 means prices are half as high again as in 2010. The US series keeps the Bureau of Labor Statistics' own 1982-84 base instead, which is why its numbers run in the hundreds. That makes index levels meaningless across countries: Britain's 149.7 and Japan's 105.5 do not say Britain is more expensive; they say British prices have risen further since 2010. To compare countries, compare the rates, or convert the money with the currency converter.
What changes the result
Why each country needs its own index
An inflation figure is a statement about one country's shops. Every statistics office builds its own basket, weights it by what its own households actually spend, and reprices it locally. Applying an American figure to euros or rupees produces a number that describes nothing.
The differences are not small. Over the 29 years above, Indian prices rose 5.48% a year and Japanese prices 0.43%. Compounded, 100 rupees of 1995 money needs 469 rupees to match it, while 100 yen needs only 113.
Each country here uses the headline index its own office publishes: the Consumer Price Index in the United States, the United Kingdom, Canada, Australia, New Zealand and Ireland; the Verbraucherpreisindex in Germany; the indice des prix à la consommation in France; the índice de precios de consumo in Spain; the consumentenprijsindex in the Netherlands; konsumentprisindex in Sweden; kuluttajahintaindeksi in Finland; and the National Consumer Price Index in Sri Lanka. The data sources listed on this page name the office behind each one and the date the figures were retrieved.
How far back the series reaches
How far back each series goes depends on what its office has published. Britain's runs to 1661 and Sweden's to 1830, which is long enough that the arithmetic starts to strain: £100 of 1900 money is about £11,850 today, but the basket behind it, tallow candles and railway fares, has almost nothing in common with the modern one. Treat very long spans as an illustration of scale, not a precise conversion. Sri Lanka's series starts in 1960 and Spain's in 1954. The year inputs are limited to the range the country actually has, and switching country moves them to a pair of years that exists there.
Deflating instead of inflating
Swap the years and the calculator works backwards: what would today's amount have been in an earlier year? This is useful for putting a modern salary or price into historical context, or for checking whether an old figure has kept up. If a pension of 20,000 in 2000 is still 20,000 in 2024, deflating shows what it now buys in the money of the year it was set.
What is not included
- Specific goods. These indices track a broad basket. House prices, university tuition and medical costs have risen faster; electronics have fallen. For a particular item, look for its own price series.
- Regional differences. Each index is a national average, and living costs inside a country move differently from city to city.
- Currency conversion. Adjusting for inflation and converting between currencies are separate steps. Do the inflation adjustment inside one country's money, then convert.
- Wages and returns. The calculator tells you what prices did, not what your savings or salary did. To see whether an investment beat inflation, compare its growth with the cumulative figure here, or use the retirement calculator, which projects both together.
Using the result
Use the adjusted amount whenever you compare money across years: a fair like-for-like raise, the real cost of something bought long ago, the real value of a fixed payment. Use the average annual rate as a planning assumption, but take it from the country you actually live in, and from a long enough span to average out the unusual years. And use the purchasing-power figure as a reminder that cash left uninvested loses value every year even when the number on the statement does not change.