Decimal Numbers in French
Virgule Replaces the Point
Updated May 2026
The single rule to internalise about French decimals is that the comma (virgule) is the decimal separator, not the point. Pi in French is written 3,14 and spoken trois virgule quatorze. The euro-dollar exchange rate is written 1,08 and spoken un virgule zéro huit. A 75% statistic might be 75,2 % and spoken soixante-quinze virgule deux pour cent. The English decimal point is wrong in French: writing 3.14 in a French document is a transparent anglicism that creates real ambiguity, because a French reader scans left-to-right and may misparse the period as a digit-grouping separator (which it sometimes is in older typographic contexts).
This page covers the virgule rule and its history, the spoken form (digit-by-digit vs as-a-complete-number), conversion from English point-and-comma notation, scientific notation, and the banking and finance precision conventions where decimals matter most. The connected rules for percentages, money, and measurements are covered in their own dedicated pages; this page focuses on the underlying decimal-separator convention.
The Virgule Rule
French uses the comma as the decimal separator in every context. Pi: 3,14. The number e: 2,71828. The square root of two: 1,41. Body temperature in Celsius: 37,5. A weight: 72,3 kg. A length: 1,75 m. The exchange rate of the euro to the dollar: 1,08. A percentage: 3,5 %. A monetary amount: 12,50 €. The convention is universal and unambiguous within French.
The virgule rule is documented in the BIPM SI brochure as the standard for all SI usage in French (and in fact for most languages other than English). The Imprimerie nationale style guide, the Légifrance publishing standard, the European Central Bank style manual, and ISO 80000-1 all converge on the comma as the decimal separator in French-language scientific and technical writing.
For digit grouping (the thousands separator), French uses a thin space, not a comma and not a period. So one million two hundred thirty-four thousand five hundred sixty-seven euros and eighty-nine cents is written 1 234 567,89 €. The space groups the integer part; the comma separates the decimal. This is the reverse of US/UK convention (1,234,567.89) and the conversion needs to happen mentally any time you read figures from one convention into the other.
Reference Table
| English | French written | French spoken | Context |
|---|---|---|---|
| 0.5 | 0,5 | zéro virgule cinq | Half, in numeric form. |
| 1.5 | 1,5 | un virgule cinq | Common decimal. |
| 3.14 | 3,14 | trois virgule quatorze | Pi to 2 decimal places. |
| 3.14159 | 3,14159 | trois virgule quatorze mille cent cinquante-neuf (or digit-by-digit) | Pi to 5 places. |
| 2.71828 | 2,71828 | deux virgule sept un huit deux huit | Euler's number e. |
| 1.41 | 1,41 | un virgule quarante et un | Square root of 2. |
| 0.001 | 0,001 | zéro virgule zéro zéro un | One thousandth (= un millième). |
| 12.50 | 12,50 | douze virgule cinquante | Common money form: 12,50 €. |
| 1.75 | 1,75 | un virgule soixante-quinze | Adult height in metres. |
| 37.5 | 37,5 | trente-sept virgule cinq | Body temperature, slight fever (°C). |
| 1,234.56 | 1 234,56 | mille deux cent trente-quatre virgule cinquante-six | US comma + point converted to FR space + virgule. |
Spoken Forms: As a Complete Number vs Digit-by-Digit
French has two ways to read a decimal number aloud. The complete-number form reads the integer part as an integer, says virgule, then reads the decimal part as a complete number. 3,14 = trois virgule quatorze. 1,75 = un virgule soixante-quinze. 37,5 = trente-sept virgule cinq. This form sounds natural for short decimal numbers (1-3 decimal places).
The digit-by-digit form reads each decimal digit individually. 3,14159 = trois virgule un quatre un cinq neuf. 2,71828 = deux virgule sept un huit deux huit. This form is preferred for long decimal sequences (4+ places), for scientific precision contexts, and for reading PIN codes, postal codes, phone numbers, and similar precision-required strings.
For phone numbers specifically, French has a third convention: pairs of digits read as two-digit numbers. The phone number 06 12 34 56 78 is read zéro six, douze, trente-quatre, cinquante-six, soixante-dix-huit. This is documented in detail on the phone numbers in French page. The pair-form does not generalise to other decimal contexts; it is specific to phone-number reading conventions.
Converting from English Notation
When you encounter an English-formatted number and need to convert it to French, the rule is simple: swap commas for thin spaces in the integer part, swap periods for commas in the decimal part. 1,234.56 (English) becomes 1 234,56 (French). 1,000,000 (English) becomes 1 000 000 (French). 3.14159 (English) becomes 3,14159 (French). The conversion needs to happen mentally for every figure imported from English source material.
The reverse direction (French to English) is equally important: spaces in the integer become commas; the decimal comma becomes a period. 1 234,56 € (French) becomes EUR 1,234.56 or €1,234.56 (English). Most French press and financial publications convert automatically when quoting foreign-source figures. Major bilingual sources (Bloomberg, Reuters, the Financial Times) publish dual-format versions of key figures.
Spreadsheet and financial-software users need to set the decimal separator preference correctly. French Excel uses comma by default; English Excel uses period. Importing CSV data between locales requires explicit conversion or risks misinterpretation: a column of US prices (12.99, 15.50, 8.75) imported into French Excel may be parsed as integers (1299, 1550, 875) if the import dialog defaults to French separators. This is a real and frequent data-quality issue in bilingual French-English business workflows.
Scientific Notation in French
Scientific notation in French follows the same conventions as elsewhere internationally, with the comma as decimal separator. 3,14 x 10^8 means 3.14 times 10 to the 8th. The base is written with virgule decimals; the exponent is written as a superscript or with the caret notation. Spoken: trois virgule quatorze multiplié par dix puissance huit (literally “three point fourteen multiplied by ten to the power eight”).
For very small numbers, the exponent is negative: 3,14 x 10^-6 = 0,00000314. Spoken: trois virgule quatorze multiplié par dix puissance moins six. The negative exponent is read with moins before the digit. French scientific writing in physics, chemistry, biology, astronomy, and engineering uses scientific notation for any number outside the range roughly 0,001 to 1 000 000.
The SI prefixes (kilo, méga, giga, téra, péta, exa for large; milli, micro, nano, pico, femto, atto for small) are an alternative to scientific notation for measurement contexts. 1 km = 1 000 m = 10^3 m, 1 µs = 10^-6 s, 1 GHz = 10^9 Hz. Both notations coexist in scientific French, with SI prefixes preferred for unit-based measurements and scientific notation preferred for dimensionless numerical results.
Frequently Asked Questions
How are decimal numbers written in French?
With a comma (virgule) as the decimal separator. So 3.14 in English is 3,14 in French. Pi: 3,14159. Euro-dollar exchange rate: 1,08. The decimal comma is the universal French convention, prescribed by the BIPM SI brochure, the Imprimerie nationale style guide, the European Union institutions, and ISO 80000-1.
How do you say a decimal number in French?
Read the integer part normally, say "virgule", then read the decimal part either digit-by-digit or as a complete number. So 3,14 is "trois virgule quatorze" (three point fourteen) or "trois virgule un quatre" (three point one four). The complete-number form is more common in everyday French; the digit-by-digit form appears in technical and precision contexts.
What is the French word for decimal point?
There is no decimal point in French; there is only the virgule (comma). Some bilingual or Anglophone-influenced writing uses "le point décimal" descriptively, but the actual symbol used and read is the virgule. In speech: "trois virgule quatorze".
Why does French use a comma for decimals?
Historical convention. The decimal comma was used in continental European mathematical practice from the 17th century. France formalised it with the metric system in 1795 and it has been standard ever since. The English-speaking world adopted the decimal point partly because the comma was already used as the thousands separator in English. The two conventions coexisted in international scientific writing until the BIPM standardised the comma in 1948 and reaffirmed it in subsequent SI brochures.
How do you handle a number like 1,234.56 (US) in French?
Convert both separators. The US 1,234.56 becomes the French 1 234,56. The comma becomes a thin space (digit grouping); the point becomes a comma (decimal separator). Get one wrong and the number reads ambiguously to a French eye. Major French press and financial publications follow this conversion automatically when reproducing US-source figures.
How do you say very precise decimals in French (scientific notation)?
For scientific notation: "trois virgule quatorze multiplié par dix puissance huit" for 3,14 x 10^8. The notation 3,14 x 10^8 itself is read with virgule for the comma. For very small numbers: "trois virgule quatorze multiplié par dix puissance moins six" for 3,14 x 10^-6. Engineering notation (in groups of three exponents) is also standard in French scientific writing.
How are decimals handled in French banking?
For currency, two decimal places are standard: 1 234,56 € (one thousand two hundred thirty-four euros and fifty-six cents). For interest rates and exchange rates, four to six decimal places are common: taux de change 1,0823 EUR/USD, taux d'intérêt 3,75 % (with the percent symbol after a non-breaking space). The Banque de France and the European Central Bank publish all their figures in this format.