This guide is for the person who proofreads a sign, a menu or a client email and suddenly doubts every apostrophe on it: the café owner choosing between “teas” and “tea’s”, the office manager writing a notice about “the Jones’ party”, the copywriter who knows the rule for its and it’s but still checks it twice. Apostrophes cause more visible errors than almost any other mark, yet the rules fit on an index card. Learn the three jobs and the handful of traps, and you can stop guessing.
The three jobs of an apostrophe
The Purdue Online Writing Lab’s apostrophe guide lists three uses. In summary, an apostrophe is used:
1. To form possessives of nouns
2. To show the omission of letters, as in contractions
3. To form the plurals of lowercase letters, as in “mind your p’s and q’s”
Everything else, including ordinary plurals such as apples, 1990s and CDs, gets no apostrophe at all.
Possessives: the core rules
Singular nouns
Add apostrophe plus s, even when the noun already ends in s in many styles:
- the editor’s notes
- the company’s policy
- James’s laptop (some style guides prefer James’)
The choice between James’s and James’ is a style decision, not a grammar error. Purdue OWL notes that most academic styles, including Chicago, APA and MLA, add apostrophe plus s, while AP style adds only the apostrophe. Pick one and use it consistently across a document or website.
Plural nouns ending in s
Add only the apostrophe:
- the editors’ notes (more than one editor)
- the companies’ policies
- the Joneses’ house (the family named Jones)
Plural nouns not ending in s
Add apostrophe plus s:
- the children’s books
- the women’s team
- the people’s vote
A quick way to get it right
Purdue OWL suggests a related check: turn the phrase into an “of the” phrase. The boy’s hat becomes the hat of the boy; three days’ journey becomes a journey of three days. Then write the owner first, in the form you mean, singular or plural. Then add the possessive ending. If you mean several teachers, write teachers, then add the apostrophe: teachers’. If you mean one teacher, write teacher, then add ‘s: teacher’s. The apostrophe never goes inside the owner’s word.
Write the owner first, exactly as you mean it. Then add the possessive ending. The apostrophe never goes inside the word.
Joint and separate ownership
When two people own something together, only the last name gets the possessive:
- Priya and Tom’s agency (one agency, owned by both)
When each owns their own, both names take it:
- Priya’s and Tom’s agencies (two agencies)
Contractions
In a contraction, the apostrophe marks where letters are missing:
| Full form | Contraction | Missing letters |
|---|---|---|
| do not | don’t | o |
| it is / it has | it’s | i or ha |
| you are | you’re | a |
| they are | they’re | a |
| who is / who has | who’s | i or ha |
| let us | let’s | u |
| of the clock | o’clock | f the |
The apostrophe goes where the letters were removed, not where the two words meet. That is why don’t has it between n and t, and why writing do’nt is wrong.
The its and it’s trap
This is the single most common apostrophe error in professional writing. Purdue OWL’s guide makes the point directly: it’s means it is or it has, and its is the possessive. Possessive pronouns never take an apostrophe.
- It’s raining. (It is raining.)
- It’s been a long week. (It has been a long week.)
- The company changed its logo. (possessive)
The test
Read the sentence aloud with it is or it has. If the sentence still makes sense, use it’s. If not, use its.
The same logic for other pronouns
None of these possessive pronouns takes an apostrophe: his, hers, its, ours, yours, theirs, whose. If you ever write your’s or their’s, the apostrophe can go.
- Whose coat is this? (possessive)
- Who’s coming tonight? (who is)
Plurals: where apostrophes do not belong
The grocer’s apostrophe, as editors call it, is an apostrophe added to a plain plural. It appears on signs and menus everywhere.
- Wrong: Fresh apple’s, two for £1
- Right: Fresh apples, two for £1
Decades and numbers
- Right: the 1990s, in her 40s
- Also right: the ’90s (the apostrophe replaces the missing 19)
- Wrong: the 1990’s (unless you mean something belonging to the year 1990)
Abbreviations
- Right: three FAQs, two PDFs, several CEOs
Most current style guides, including those used by news organisations, use no apostrophe for these plurals.
Single letters
Lowercase letters are the exception. Purdue OWL describes this rule as more typographical than grammatical: p’s and q’s is easier to read than ps and qs. Capital letters, numbers and symbols do not need the apostrophe, so three G4s and too many &s are correct.
Possessives with names, brands and time
Brand names
Follow the company’s own spelling if it has one. Some brands drop the apostrophe from their names; others keep it. When you write about a brand in a possessive, add the ending as normal: Google’s guidance, Tesco’s prices.
Expressions of time and value
These use apostrophes too, because they are possessive in form:
- a week’s notice
- two weeks’ notice
- a day’s pay
- five dollars’ worth
People often miss the second one. If the time is plural, the apostrophe moves after the s.
Apostrophes in different kinds of writing
Business documents and websites
Errors here cost credibility. A stray apostrophe on a pricing page or menu is noticed. Run a search for “‘s” before you publish and check each one against the rules above.
Academic writing
Many academic styles discourage contractions in formal papers. Check your guide before writing don’t instead of do not.
Emails and social posts
Contractions are normal and make writing sound natural. The possessive and its rules still apply.
Five apostrophe questions people ask
Do I write “the Smiths” or “the Smith’s” on a card?
“The Smiths” if you mean the family. No apostrophe, because it is a plain plural. Write “the Smiths’ house” when the family owns something.
What about words that end in s and look plural, such as news or physics?
They are singular, so treat them that way: the news’s impact is correct but clumsy. A rewrite such as the impact of the news reads better.
Is it “the boss’s” or “the boss'”?
Most guides prefer boss’s, because you pronounce the extra syllable. If you would say “bosses” aloud, write boss’s.
Should a shop be called “Mikes Bikes” or “Mike’s Bikes”?
Grammatically, Mike’s Bikes. A business is free to register its name without the apostrophe, but in your own writing about another brand, follow how they spell it.
Do I need an apostrophe in “Farmers Market”?
Both farmers’ market and farmers market are widely used; the first treats the market as belonging to farmers, the second treats farmers as a description. Choose one and keep to it.
Practice: fix these sentences
1. The dog wagged it’s tail.
2. Both manager’s signed the form.
3. We sell CD’s and DVD’s.
4. I need three day’s notice.
5. Is this your’s?
Suggested answers: (1) its tail (2) managers’ (3) CDs and DVDs (4) three days’ notice (5) yours
Apostrophe checklist
- Possessive singular: noun plus ‘s
- Possessive plural ending in s: add only an apostrophe
- Plural not ending in s: add ‘s
- Contraction apostrophe sits where the letters were removed
- It’s only when you mean it is or it has
- No apostrophe in plain plurals, decades or abbreviation plurals
- No apostrophe in his, hers, its, ours, yours, theirs, whose
- One consistent choice for names ending in s
Takeaway
An apostrophe does three jobs: it shows possession, marks missing letters, and occasionally clarifies the plural of a single letter. Write the owner first, then add the ending; test it’s by saying it is; and remove every apostrophe that has crept into a plain plural.
