I read in a grammer book that nouns expressing number and weight (when preceded by numerals ) are not pluralized, as: five dozen apples, five head of cattle, four yoke of oxen, etc.

My question is weather it is true in the case of 'liter'. I have some possible cases in mind.

  1. Five liters of water.
  2. Five liters water.
  3. Five liter water.
  4. Five-liter water.

Which of the above cases (1 to 4) are correct and which of the above cases are wrong?

  • Some nouns only are not pluralized. The rest are. Dec 25, 2019 at 9:51
  • No reference here so not an answer, but this generally doesn't apply to units of measure such as liters, pounds, miles, etc. -- those get pluralized. You would say that you have five liters of water. (You could also say that you have five thousand milliliters of water)
    – A C
    Dec 25, 2019 at 10:35
  • Certain units of measure are not pluralised - dozen, hundred, thousand, (etc). Also to do with livestock - head of cattle or sheep, yoke of oxen. With game, neither the unit nor the noun is plural: five brace of partridge, pheasant, snipe, etc. Big game hunters do not pluralise animal nouns, e.g. I shot five lion, ten gazelle, three moose. Dec 25, 2019 at 11:54
  • 1
    Your (3) and (4) are identical.For me, (1) is correct and (2) is so so. In US, we call Five-liter can or water bottle to show the size of the container. Dec 26, 2019 at 8:56

2 Answers 2


Most of the words that are singular after a number are quite old fashioned.

Words like dozen (12), score (20) and gross (144) can be used about anything, and are treated the same as numbers:

  1. they are singular when preceded by a determiner or a multiplying number
  2. it is not necessary to use of between a number and the word its refers to
  3. the plural is only used for approximate numbers.

a dozen eggs
five dozen eggs
dozens of people came to the shop today

For words that have a much more limited usage like head (people and cattle), yoke (oxen) and brace (game birds, but can be used for other things), only rule 1 applies.

a yoke of oxen
five head of cattle
several brace of pheasants

The word pair is widely used in modern english, and this conforms to the normal rules for nouns:

a pair of socks
five pairs of socks
several pairs of socks

For older (imperial) weights, these Ngram graphs for pound and ton show that these units of weight were historically used as a singular after a number, but even a hundred years ago it was a lot more common to use a plural after a number. For stone, the singular and plural are a lot closer, but for ounces, there is no evidence of usage of a singular after a number and for hundredweight instances of the plural are in the minority.

For modern (metric) weights (gram, gramme, kilo, kilogram and tonne), all use a plural after a non-unity number, and also use of.

When an abbreviation is used, whether metric (kg) or imperial (lb), the singular is more frequently used and the of is usually included.

To answer your specific question about litres: Litre (UK)/liter(US) follows the same conventions as other metric units: it uses a plural after a non-unity number and requires of, so the first option is the correct version.

1 - Five liters of water.

You may occasionally see the second option, when the writer wishes to save space.

I think that you are unlikely to see 3 and 4, though you may see the abbreviation

5 l water

  • In British game usage, we say one, two three (etc) brace of pheasant. Animals that are hunted & killed are referred to in the singular. en.wikipedia.org/wiki/English_plurals Dec 25, 2019 at 12:56
  • 1
    @MichaelHarvey According to NGRAM, brace of pheasants is, and always has been, more common than brace of pheasant. Likewise for pigeons and partridges, but grouse is always grouse. books.google.com/ngrams/…
    – JavaLatte
    Dec 25, 2019 at 13:09
  • I didn't (and don't) learn to speak from Ngrams. Dec 25, 2019 at 14:24
  • @MichaelHarvey; none of us did. Ngrams reflect the natural variation of usage in written language. We can use it to understand the differences between the way we use language and the way other native speakers do, and to see how usage changes over time..
    – JavaLatte
    Dec 26, 2019 at 7:10
  • Is “a dozen of eggs” wrong? Or the “of” is just not necessary in it? May 3, 2020 at 5:07

You can say

a five-liter bottle

which is pretty massive if you think about it, but it's rare to read or say

5-liter water

Instead English native speakers will say and write (see @JavaLatte's answer)

Five litres of water

Note the hyphen which makes five-liter or 5-liter into a single noun phrase, which acts like an adjective. Compare “5 star hotel“ (never five stars hotel) and five-year-old boy, see Google news for examples of usage.

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