Do you say "2 Byte" or "2 Bytes"? Which one is correct? If both is possible, when to use what?

The same question would come to my mind for my own language: German. So, there has to be a technical answer.

  • 6
    Why would you use 2 Byte? I have always said Gigabytes, Megabytes, etc., without even wondering. Just like any other measurement unit? – MadWard Jun 10 '16 at 14:51
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    Would you provide some context?1 – Cardinal Jun 10 '16 at 14:51
  • see this title: programmers.stackexchange.com/questions/203254/… you also say "meters" and "yards" as plural, right? you you say the plural with "s" is simply wrong? – Willi Mentzel Jun 10 '16 at 14:51
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    Byte is a countable word, so it would be two bytes. The thing is that when we use a countable word or phrase as though it were an adjective, we don't pluralize it, so you will see "a two-byte variable", or "a three-meter ladder" or "a five-man team", despite the fact that byte, meter, and man are all countable and pluralizable. – stangdon Jun 10 '16 at 14:54
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    "Two bytes" would be correct for enumerating an amount of memory > 1 byte. However, if referring to an in-memory object it would be "a two-byte integer", "an eight-byte floating point value", "a 128 megabyte L2 cache", etc. – Bob Jarvis Jun 11 '16 at 0:28

Both are possible, although the former would normally employ a hyphen.

When used as an adjective, 2-byte refers to size of something:

The computer's memory is organized into 2-byte words.
The token is stored as a 2-byte variable.
This will need to be stored as a 2-byte character.

When used as a plural noun, the 2 is simply a quantifier. However, in this case, you might see the word spelled out (as is often the case with numerals less than 10):

Each word in memory can be broken into two bytes.
The token is stored as a variable which takes up two bytes.
We will need to store this character in two bytes; it won't fit in one.

  • 18
    In this it is like all (or nearly all) other measure-words in English: foot, pound, metre, ton, hectare, litre ... – Colin Fine Jun 10 '16 at 16:45
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    A two-man team. – Tᴚoɯɐuo Jun 10 '16 at 17:55
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    @ColinFine Yes, when used as an adjective, you follow this rule. Ten foot pole, five pound slab, two ton vehicles, three liter bottles, and so on. When you're using the measure word as an adjective, it is singular, while when used as a quantifier, it is plural (if not exactly 1). – phyrfox Jun 10 '16 at 17:58
  • Additional tip: you can combine digits with written-out numbers in cases like: "An xmm register holds four 32-bit floats". I have to admit I usually write "32bit", not "32-bit" or "32 bit", although the usual convention for units is to leave a space. (b and B are the units for bits and bytes, respectively, but the whole word can also work as a unit, I think). I think a hyphen is perfect to associate the number with the unit more strongly when it's a countable unit (integer only). – Peter Cordes Jun 11 '16 at 7:37
  • @PeterC - Yes, a space is the usual convention, although there are some exceptions, like when you use M for milliion in money (the project cost $32M, e.g.). As for large amounts of memory, I think the space is often omitted (as in, an 8GB thumb drive),, which is why some may be comfortable writing "32bit". Interesting ngram. – J.R. Jun 11 '16 at 8:10

To add to J.R.'s answer, note that in English, adjectives never change their form. Thus, any noun which is being used as an adjective cannot use its plural form. In addition, compound adjectives (multiple words functioning as a single adjective) are separated by hyphens. Compound nouns usually (but not always) are not, at least in American English.


  • "He's two meters tall." In this sentence, two is an adjective modifying the noun meters.
  • "That's a two-meter-tall man." Here, two-meter-tall is a compound adjective modifying man. The key here is that meter is being used adjectivally.
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    It's my observation that hyphens in compound adjectives have become increasingly optional in practice, both in formal and informal writing, which is unfortunate since they lend a significant degree of clarity. – SevenSidedDie Jun 11 '16 at 2:53
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    This may be due in part to the fact that writers don't usually understand English on this level; this is the domain of English teachers, editors, and proofreaders. In the Internet age, it appears that editors and proofreaders have become endangered species: Even the major online publishers give little evidence of having any in their employ. – Scott Severance Jun 11 '16 at 4:39
  • The use of plural nouns as an adjective is on the rise: numbers crunching, covers band, birds conservation, jobs report, games arcade, drugs dealer, Cubs fan, etc. – Alan Carmack Jun 11 '16 at 13:50
  • @AlanCarmack: That may be context-specific. The only examples you've cited which I've heard of is jobs report and Cubs fan. I would argue that they are special cases: It would seen strange to many people to use the singular form of a sports team's name, so that could explain Cubs fan. I've heard jobs report and would consider it an outlier in AmE, though several of your examples I could imagine encountering in BrE. It may be that the use of plural nouns as adjectives is on the rise in certain varieties of English, but I know of no evidence that it is generally the case across the board – Scott Severance Jun 11 '16 at 23:06
  • By the way, at least in AmE, the opposite is common in informal spoken English. One will frequently hear expressions such as: "He's six foot tall." This is especially common in rural areas. This would suggest to me that, at least among speakers who follow this pattern, the no-plural-adjectives rule is still alive and well. – Scott Severance Jun 11 '16 at 23:10

It depends.

  • If you want "two bytes" as a compound adjective, use This is a 2-byte-long program..
  • If you want "two bytes" as a noun, use This program has size of 2 bytes..

Note that in the compound adjective form, 1 is often omitted.

  • This is a 1-byte-long program. -> This is a byte-long program.

Under most situations, the proper term should be "2 Bytes" rather than "2 Byte". The "2" here is being interpreted as a set of two units, thus requiring pluralization. See Here. This will continue for N numbers (2 bytes, 3 bytes, ... , N bytes).

However, more rarely when the system is the topic, such a "2-byte system", there is only a singular object, not requiring pluralization.

  • This is pretty much the same as the accepted answer, which was posted over a day earlier. – Criggie Jun 11 '16 at 23:19
  • Actually I posted this a day before the accepted answer. Then the question was deleted and reposted here, and I answered it within an hour or so of the question being posted here. Note the "asked 2 days ago" and "answered 2 days ago" on both mine and the accepted answer. Please see my post. Please do not down vote posts that answer the question. – MathFromScratch Jun 13 '16 at 13:51

We can create a better informative answer if we switch away from bytes to some other unit. How about the foot (unit of length)?

Key sentences:

My father caught a four foot sturgeon last weekend.

Yes, it was literally four feet long.

Its length was four feet.

"Four foot sturgeon" is a compound noun phrase, the head of which is "sturgeon". The other nouns in a noun phrase which modify the head do not carry a plural marker. We can have "four foot sturgeon" but not "four feet sturgeon".

In "four feet long", the grammar is different. Here "four feet" is a complete noun phrase on its own, which modifies the adjective "long". A noun denoting a quantity can modify a dimension: "(it is) four feet long" answers the question "how many feet (is it) long?"

If we drop the plural, we change the structure: "four-foot-long" is possible, but now it's a compound adjective, because "four-foot" isn't a grammatical noun by itself. (In formal writing, we write this with the hyphens, as I have it. Another example of this pattern "three-year-old boy" and of course "ten-byte-long string".)

These quantity-indicating adjective phrases like "four-foot-long", "ten-byte-long", or "three-years-old" adjectives aren't used as complements to a noun under the verb "is":

The boy was { *three-year-old / three years old }.

*The character string is three { *byte | bytes } long.

The pond was only four { ?foot | feet } deep.

It's a curious situation in English because adjectives usually work as is-complements: we can say "blue sky" and "the sky is blue"; or "sad song" as well as "the song is sad".

This is something to watch out for.

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