French flag

Giving measurements in French with 'long de' and 'de long'

In English, a measurement simply sits in front of the adjective: two metres long, ten metres high, three centuries old. French never glues the number straight onto the adjective. It links the two with de, and it can do so in two orders: long de deux mètres or deux mètres de long.

English speakers tend to translate word for word and produce something like deux mètres long, which sounds wrong to any French ear. The fix is easy once you know it: whenever you give a size, a depth, a duration or an age with words like long, haut, large, profond or vieux, add de.

Word list
hautmA1 tall dix mètres de haut / haut de dix mètres = ten metres high longmA1 long deux mètres de long / long de deux mètres = two metres long longmA1 long long de deux heures = two hours long vieuxmA1 old vieux de trois siècles = three centuries old âgémA2 old âgé de huit ans = eight years old largeA2 wide trois mètres de large / large de trois mètres = three metres wide profondmA2 deep profond de vingt mètres = twenty metres deep épaismB1 thick épais de trente centimètres = thirty centimetres thick hauteurfB1 height dix mètres de hauteur = ten metres high largeurfB1 width trois mètres de largeur = three metres wide longueurfB1 length deux mètres de longueur = two metres long profondeurfB1 depth deux mètres de profondeur = two metres deep épaisseurfB2 thickness un centimètre d'épaisseur = one centimetre thick
How it works

French has two common patterns, and both need de.

  • Measurement + de + dimension word, usually after faire, mesurer or avoir: Le mur fait trois mètres de haut. This is the most frequent pattern in everyday speech.
  • Adjective + de + measurement, usually right after a noun: une rivière large de vingt mètres. This one is a little more written, and the adjective agrees with the noun.
La table fait deux mètres de long.
(The table is two metres long.)
Ils ont traversé une rivière large de vingt mètres.
(They crossed a river twenty metres wide.)

Rule of thumb: a number and a dimension word never touch directly. There is always a de between them.

The words
Length, height, width, depth, thickness

The adjectives long, haut, large, profond and épais work in both patterns.

Mon jardin fait trente mètres de long.
(My garden is thirty metres long.)
Ce mur a trois mètres de haut.
(This wall is three metres high.)
C'est un lac profond de cent mètres.
(It is a lake a hundred metres deep.)
La maison a des murs épais de quarante centimètres.
(The house has walls forty centimetres thick.)
The nouns

Instead of the adjective, you can use the matching noun after de: longueur, largeur, hauteur, profondeur, épaisseur. It sounds slightly more precise and technical, like English in height or in depth.

La tour mesure cinquante mètres de hauteur.
(The tower is fifty metres high.)
La piscine fait deux mètres de profondeur.
(The pool is two metres deep.)
Le terrain fait vingt mètres de largeur sur quarante de longueur.
(The plot is twenty metres wide by forty metres long.)
La planche a deux centimètres d'épaisseur.
(The board is two centimetres thick.)
Time and age

The same de appears when long describes a duration and when vieux or âgé gives an age.

Nous avons eu une attente longue de plusieurs heures.
(We had a wait several hours long.)
C'est une tradition vieille de plusieurs siècles.
(It is a centuries-old tradition.)
Une fillette âgée de huit ans a gagné le concours.
(An eight-year-old girl won the competition.)
Watch out
Agreement

In deux mètres de long, the word after de never changes: une table de deux mètres de long. In the other order, the adjective agrees: une route longue de deux kilomètres.

Elision

Before a vowel, de becomes d': trois centimètres d'épaisseur. With épais, French prefers the noun here, so say d'épaisseur rather than d'épais. With depth, de profondeur is the safe choice, and de profond sounds casual.

Age has only one order

You can say vieux de trois siècles or âgé de vingt ans, but never trois siècles de vieux. Use vieux de for objects, buildings and traditions. For a person, say âgé de or simply use avoir: il a vingt ans.

Narrow things

Words like étroit or bas are not used with a measurement. A narrow street is still large de trois mètres, just as English says three metres wide, not three metres narrow.

Summary

Never put a number straight before or after a dimension word in French. Link them with de: either faire deux mètres de long (the most common, with no agreement) or long de deux mètres (after a noun, with agreement). The same de appears with the nouns hauteur, profondeur or épaisseur, and with durations and ages such as vieux de trois siècles and âgé de huit ans.