Apostrophes to Show the Plurals of Abbreviations or Awkward Plurals

The Quick Answer
If you have an awkward plural (usually of a letter, a number, or an unusual abbreviation), you can use an apostrophe to assist your readers. For example:
  • Hawaii is spelt with two i's.
  • She used six and's in one sentence.

Using Apostrophes to Show the Plurals of Abbreviations and Awkward Plurals

The first thing to make clear before we start this lesson is that apostrophes are not normally used for forming plurals. (This is covered more in the lesson apostrophe errors with plurals.)

Using an apostrophe to form a plural is usually a grammatical howler. For example:
  • She will not eat banana's.
  • Is it true that pearl's melt in vinegar?
However, sometimes, a plural is so awkward, it is permissible to use an apostrophe to assist your readers. For example:
  • There are two a's in accommodation.
  • Your 2's look like your 7's.

Assist your Reader

The advantage of using an apostrophe is that the abbreviation, letter, or number is instantly recognisable. However, apostrophes can also be used to show possession. Therefore, when apostrophes are used to show plurals, it can lead to ambiguity.

Look at this newspaper heading:
  • MP's Plan Failure
In this example, the writer used an apostrophe to show a plural, and he created ambiguity. Is this title about (1) MPs planning to fail? or (2) the failure of an MP's plan? It's unclear.

You should only use an apostrophe in the plural of an abbreviation, a letter, or a number to assist your reader.

Using 's to show a plural can lead to ambiguity. Even if there is no real ambiguity, it will at least make the reader pause momentarily to check whether the apostrophe shows a plural or a possessive noun.

Look at these examples:
  • You use too many and's in your writing.
    • (The apostrophe assists the reader in this example.)

  • There are two consecutive i's in the words skiing and taxiing.
    • (The apostrophe assists the reader in this example.)

Do not Use an Apostrophe for the Plural of a Normal Abbreviation

It is worth reiterating this point. Do not use apostrophes for the plurals of normal abbreviations. For example:
  • He had 4 CCJ's against him.
  • He had 4 CCJs against him.
    • (Note: CCJ = County Court Judgment)

  • M.O.T.'s
  • M.O.T.s
    • (Note: MOT = Ministry of Transport / also Ministry of Transport test)

  • MOT's
  • MOTs
Note: It is often the writer's choice whether to use full stops / periods in abbreviations.

Read more about full stops (periods) in abbreviations.

Do Not Try Too Hard to Avoid the Apostrophe

Of course, there are other ways to show an awkward plural. For example:
  • Hawaii is spelt with two "i"s.
  • Hawaii is spelt with two Is.
  • She used six ANDs in one sentence.
  • She used six ands in one sentence.
These methods are acceptable, but the apostrophe version is usually far neater and clearer.
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See Also

Using apostrophes The apostrophe error with plurals Apostrophes in time (temporal) expressions Apostrophes replace letters Apostrophes show possession Full stops (periods) in abbreviations