Apostrophe Mistakes You Might Be Making (And How to Fix Them!)

Apostrophe use is one area where both English learners and native English speakers make A LOT OF mistakes! Apostrophes are used to show possession, and to indicate missing letters in contractions.

Follow these simple rules to avoid common errors and make your writing clearer and more professional.

Plural nouns: no apostrophe needed!

One of the most common apostrophe mistakes occurs when forming plurals. You might see signs with phrases like:

❌ “ATM’s” instead of “ATMs”

❌ “The 1980’s” instead of “The 1980s”

❌ “Open on Sunday’s” instead of “Open on Sundays”

In these cases, the apostrophe is unnecessary because we are simply forming a plural, not showing possession.

ATMs (not ATM’s) refers to multiple automatic teller machines. Since we wouldn’t say two machine’s, we shouldn’t say ATM’s either.

The 1980s (not 1980’s) refers to a decade made up of multiple years. Just as we say two years  (not two year’s), we should write 1980s without an apostrophe.

Sundays refers to multiple Sundays. We wouldn’t say two Sunday’s, so we don’t say open on Sunday’s either.

The exception: pluralising individual letters

The one case where an apostrophe is used to form a plural is when pluralising single letters. This prevents confusion:

✔ There are two m’s in Emma.

❌ There are two ms in Emma. (Without the apostrophe, “ms” could be misread as "Ms.")

✔ Some people drop their t’s and h’s.

❌ Some people drop their ts and hs. 

A secial case: “dos and don’ts”

The phrase “dos and don’ts” refers to what you should and shouldn’t do in a particular situation. The plural of do is dos, so adding an apostrophe is considered by many to be incorrect. However, since the singular do is rarely used, some writers feel that adding an apostrophe makes it clearer. This is more common in US than UK English (the AP style guide prefers do’s). If you're writing professionally, check your style guide!

Contractions: apostrophe needed

A contraction is a shortened form of a word or group of words created by omitting certain letters and replacing them with an apostrophe ('). Contractions are commonly used in spoken and informal written English. They should not be used in formal written English, such as academic essays or job application emails.

Here are some of the most common contractions:

I am = I’m

He is = He’s

We have = We’ve

You are = you’re

Will not = won’t

Did not = didn’t

Cannot = can’t (notice that cannot is one word – NOT can not)

I would / I had = I’d (watch this short video to learn a simple trick to tell the difference!)

Possessive nouns: using apostrophes correctly

Apostrophes show ownership or possession, and their placement depends on whether the noun is singular or plural.

1. Singular Possession

For singular nouns, add ’s to show ownership:

✔ The girl’s jacket (the jacket belonging to one girl)

✔ My friend’s house (the house that belongs to my friend)

2. Plural Possession

If the noun is plural and ends in s, just add an apostrophe after the s:

✔ The girls’ jackets (the jackets belonging to multiple girls)

✔ My parents’ house (the house of both parents)

If the plural noun does not end in s, add ’s as you would for a singular noun:

✔ The men’s books (the books belonging to the men)

✔ The children’s toys (the toys belonging to the children)

3. Possessive proper nouns (names)

For names ending in s, UK and US style guides differ:

• In UK English, pronunciation determines whether you add ’s or just ’. If you pronounce an extra s, write it out:

  ✔ James’s hat (because we say James’s)

  ✔ Charles Dickens’s novels (because we pronounce Dickens’s)

• If no extra s is pronounced, just add an apostrophe:

  ✔ My parents’ house (not parents’s)

  ✔ The ladies’ toilets (not ladies’s)

• In US English, add ’s (Chicago and AP).

• Exception: If the following word starts with s, just add ’ (AP only).

  ✔ James’ scissors

As with dos and don’ts, if you’re writing professionally, check your style guide! If you’re a student, check with your department, or take a look at some academic articles in your subject area and see which style they follow.

If you are writing for yourself, feel free to choose whichever you prefer. Just make sure you are consistent. Pick one style and stick with it!

4. Plural proper nouns

When a family name is pluralised, add only an apostrophe:

✔ The Joneses’ car (The car belonging to the Jones family)✔ The Smiths’ party (The party hosted by the Smith family)

5. Joint vs individual possession

What happens when we talk about things that belong to more than one person? Should we say, “That’s John’s and Robert’s house” or “That’s John and Robert’s house”?

If two or more people share ownership of the same thing, only the final name gets an apostrophe:

✔ That’s John and Robert’s house. (One house belonging to both John and Robert.)

✔ Maths is Anna, Helen, and Mark’s favourite subject. (Anna, Helen, and Mark all love maths.)

If each person owns separate things, both names take an apostrophe:

✔ Martin’s and Sarah’s projects were excellent. (Each person had their own project.)

✔ Charlie’s, Rebecca’s, and Hannah’s mums met when they were at school. (Charlie’s mum, Rebecca’s mum, and Hannah’s mum all met when they were at school.)

Possessive adjectives and pronouns

A very common mistake is the use of an apostrophe with the possessive adjective its. Possessive adjectives and pronouns are already possessive, so adding an apostrophe is redundant!

✔️ The cat stretched its legs.   

❌ The cat stretched it’s legs.

We also often see this mistake with the relative possessive pronoun, whose.

✔️ Whose pen is this?

❌ Who’s pen is this?

✔️ That’s the man whose dog lost its ball.                       

❌ That’s the man who’s dog lost it’s ball.

By keeping these simple rules in mind, you can use apostrophes correctly and confidently! If you’re writing for a specific publication, check their style guide to ensure consistency. And if you're ever unsure, just remember – apostrophes don’t make plurals!

To check your work for apostrophe errors, try an AI writing tool! LanguageTool and Grammarly are both excellent choices.

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