What was your money worth?

For a given country and two years, the calculator multiplies your amount by the ratio of the consumer price level in the target year to the consumer price level in the source year. If a basket cost 100 units in the source year and 196 units in the target year, your 50,000 in the source year had the purchasing power of 98,000 in the target year.

Cumulative inflation is the same ratio minus one. Average annual inflation is the geometric mean per year. That is the entire computation.

Each country sources its CPI from its national statistical office where possible: BLS for the United States, ONS for the United Kingdom, Destatis for Germany, INSEE for France, ISTAT for Italy, INE for Spain. For Eurozone countries, the pre-1999 series uses the legacy currency's national CPI, then chains to the euro at the official 1999 conversion rate. Eurostat HICP is used post-1996 for cross-country harmonisation.

For emerging markets and post-Soviet successor states, the source order is national statistical office, then IMF International Financial Statistics, then World Bank World Development Indicators. Penn World Tables and Maddison Project Database are used only for editorial commentary, never for direct calculation.

Each country's earliest available year is shown when you select it. Years before that are not available and the picker disallows them. The methodology never extrapolates beyond the source range.

For source years before euro adoption, the tool reads the legacy currency's CPI from its national statistical office. Deutsche Marks, French Francs, Italian Lire, Spanish Pesetas, Dutch Guilders, Austrian Schillings, Belgian Francs, Irish Pounds, Portuguese Escudos, Finnish Markka, Luxembourg Francs, and Greek Drachmas all chain through the official 1999 fixing rates to the euro.

The result reads naturally: "DM 30,000 in 1980 had the purchasing power of EUR X today." It is a price-basket statement, not a wealth equivalence. The methodology is honest about that limit.

Some countries experienced hyperinflation episodes during which CPI is unreliable as a measure of purchasing power. Annual inflation above 100 percent breaks the assumption that a price-basket conversion captures anything real. Argentina (1989-1990 and chronic 2018 onward), Brazil (1989-1994), Yugoslavia (1992-1994), Zimbabwe (2007-2009 and chronic), Venezuela (2017 onward), Lebanon (2019 onward), Hungary (1945-1946), Weimar Germany (1922-1923), and the post-Soviet successor states (1991-1995) are examples.

For these years, the calculator either disables calculation across the rupture, or shows the answer with a strong directional warning. The default behaviour is to refuse cross-rupture queries and tell the user why.

CPI tracks the price of a basket of goods that approximates a typical household's spending. The basket is reweighted periodically, sometimes annually. Quality changes over time are partially captured by hedonic adjustment but not perfectly. A 1990 mobile phone and a current-year smartphone are both "phones" in the basket, but the experience of each is incomparable. This is a known limit of any price-index method.

CPI also does not capture changes in housing tenure, public-service quality, environmental conditions, or working hours. A purchasing-power conversion answers the question "what did the same basket cost", not "what was life like".

Why doesn't this go back further for my country? Reliable CPI series do not exist before a certain year for most countries. The picker shows the earliest available year. We do not extrapolate beyond it.

What does CPI mean? Consumer Price Index. A measure of the cost of a representative basket of consumer goods, indexed to a base year.

Why are calculations across hyperinflation years disabled? During hyperinflation, prices change faster than the basket can be measured, and the conversion produces nonsense numbers. The tool refuses rather than mislead.

How accurate is this for the 1980s? For the United States, United Kingdom, and most of Western Europe, very accurate (within 1-2 percent). For other countries, accuracy depends on the quality of the underlying CPI series.

Can I compare my grandparent's salary? The tool can give you the equivalent price-basket figure. It will not tell you whether your grandparent was wealthy. That depends on the country, the era, and many things CPI does not measure.

Data is refreshed annually as national statistical offices publish their final CPI figures.