French Franc to Euro Inflation Calculator (1901–2025)

Converting a French franc amount into today’s euros takes two separate operations: the currency change (old francs, new francs, euros) and the correction for inflation accumulated since. The fixed conversion rate alone — 1 euro = 6.55957 francs — only answers the first: it tells you what the sum would be worth nominally, not what it could buy.

The converter below does both at once, over 1901–2025, using the official purchasing-power transformation coefficients published by INSEE, France’s national statistics institute — the same table that powers INSEE’s official converter. Enter an amount and its year: the tool deduces the currency of the time, shows the equivalent in 2025 euros, the price multiplier over the period, average annualized inflation, and the reverse conversion.

How the conversion works

The conversion chains two steps. First, monetary erosion: the INSEE coefficient of the origin year measures how many times French consumer prices were multiplied between that year and 2025, based on the annual average of the consumer price index. Second, the currency change, applied according to the year entered: an amount dated 1959 or earlier is read in old francs (divided by 100 to obtain new francs), an amount from 1960 to 2001 in francs (divided by 6.55957 to obtain euros), and an amount from 2002 onwards directly in euros.

Three examples, computed with the tool’s own coefficients: 100 francs of 1980 correspond to €50.35 of 2025 — prices were multiplied by 3.30 over the period, i.e. average inflation of 2.7% per year for 45 years. 1,000 old francs of 1950 are worth €33.73 of 2025. And €100 of 2010 equal €127.70 of 2025: even without any currency change, fifteen years of moderate inflation remove nearly a fifth of the purchasing power of a sum left untouched. Read in reverse, €100 of 2025 would have represented about 198.62 francs in 1980.

What the INSEE coefficients measure — and their limits

The coefficients come from the INSEE series “Coefficient de transformation de l’euro ou du franc” (base 2025), built on the general consumer price index in annual averages: the index for urban households headed by a manual or clerical worker from 1901 to 1992, the all-households index for metropolitan France from 1993, and for the whole of France from 1999. The tool embeds this table as published and reproduces INSEE’s own worked examples to the cent — 3.80 francs of 1995, the price of a baguette at the time, come out at €0.93 of 2025 in both tools.

Three caveats, which INSEE itself states. The 1914–1918 and 1939–1949 periods, marked by very high inflation and statistical disruptions, rely on reconstructed data: the official coefficients are used as published, but uncertainty is higher there — those zones are shaded on the chart. The coefficients are published rounded, which degrades the relative precision of the oldest conversions (before roughly 1949). And these values are statistical and indicative: they cannot serve as a legal reference. One scope note: home purchases, treated as investment, are excluded from the consumer price index (rents are included) — the tool says nothing about French house prices. The series ends in 2025, the latest complete year published; results are expressed in 2025 euros and the table is updated annually.

FAQ

Why divide by 6.55957?

It is the irrevocable conversion rate between the franc and the euro, fixed by the Council of the European Union on 31 December 1998: 1 euro = 6.55957 francs. It is not a fluctuating exchange rate but a definition. It converts the currency, not purchasing power: 100 francs of 1980 are €15.24 nominally, but €50.35 once 1980–2025 inflation is taken into account.

Old francs or new francs: how does the tool decide?

By the year. The new franc, introduced on 1 January 1960, is worth 100 old francs: an amount dated 1959 or earlier is read in old francs, an amount from 1960 to 2001 in francs, and an amount from 2002 — the year euro cash entered circulation — in euros. The deduced currency is displayed explicitly. INSEE’s official converter lets you pick any currency for any date; deducing it from the year matches historical usage and avoids the classic mistake of reading a 1950s figure in new francs. That is also why mid-century French salaries sound astronomical: “50,000 francs a month” in 1955 are old francs — 500 new francs — one hundred times less than the figure suggests.

Go deeper

• How INSEE calculates inflation — the basket, weights and limits of the CPI underlying this tool’s coefficients.
• US inflation calculator — this tool’s sibling, on US CPI data.
• Real return after inflation calculator — the same erosion mechanism, applied to an investment.
• All Eco3min financial tools — simulators and calculators to test an assumption before deciding.

Last updated — 13 July 2026