When to Use Apostrophe S ('s) | Guide & Examples

An apostrophe followed by an “s” is used in English to create possessive nouns. For example, the noun dog becomes dog’s when you refer to something belonging to the dog, such as “the dog’s ball.”

With plural nouns ending in “s,” you add the apostrophe after “s” and do not add an additional “s.” For example, the plural noun parents becomes parents’ (not “parent’s” or “parents’s”) in a phrase like “my parents’ car.”

An apostrophe can also be used to indicate a contraction (shortening of a word or phrase). So an apostrophe “s” may instead be short for the word “is” or “has,” as in “it’s” (“it is” or “it has”). In this context, it doesn’t indicate possession.

When to use apostrophe “s”

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Apostrophe “s” to form possessive nouns

An apostrophe followed by an “s” is the most common way to indicate possession (ownership) in English. This applies to most singular nouns and also to plural nouns that don’t end in “s” (e.g., “women” becomes “women’s”).

It also applies to singular nouns that end in “s” (e.g., “the analysis’s implications“), acronyms (e.g., “the BBC’s funding”), proper nouns (e.g., “Jack’s cat”), and compound nouns (where the apostrophe “s” is always added to the final word: “his brother-in-law’s motorbike”).

Examples: Apostrophe “s” for possessive nouns
Sorry about the heat. The building’s air conditioning is broken.

This symphony’s importance to the development of classical music is considerable.

Children’s likes and dislikes can change quickly.

Martha’s son is under the au pair’s supervision.

Exception: “For goodness’ sake”

An exception is usually made in expressions like “for goodness’ sake.” Here, the “s” is left out (even though “goodness” is singular) to avoid having an awkward series of “s” sounds in one place.

The same applies to other singular nouns ending in an “s” sound when they are used before “sake.” The other common examples are “for conscience’ sake” and “for appearance’ sake.”

Names ending in “s”

There’s some disagreement about whether to add the extra “s” for the possessive form of names ending in “s”: for example, do you write Darius’ or Darius’s?

Language authorities differ in their recommendations, but since styles guides like MLA, APA, and Chicago recommend adding the “s,” we advise going for this approach (e.g., “Darius’s reign”).

Note that adding an apostrophe before the existing “s” without adding an extra “s” (e.g., “Dariu’s”) is always wrong.

With words in italics or quotation marks

When forming the possessive of a noun that’s written in italics (e.g., the title of a book or movie), the apostrophe “s” should not be in italics, because it’s not part of the title. Write the apostrophe and the “s” without any special formatting.

  • The Great Gatsby’s themes

If the noun is written in quotation marks (e.g., the name of a short story or a song), the combination of quotation marks and apostrophe is hard to read and should be avoided. Form the possessive in a different way, such as by using “of,” in these cases.

  • “The Tyger”’s rhyme scheme
  • “The Tyger’s” rhyme scheme
  • The rhyme scheme of “The Tyger”

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Apostrophe after “s” for possession with plural nouns

Plural nouns that end in “s” (most plural nouns) form the possessive with an apostrophe after the “s,” without adding a second “s.”

For example, to describe the roofs of multiple houses, you would write “the houses’ roofs” (“the house’s roofs” would refer to multiple roofs on one house).

This also applies to nouns that look plural even though they’re singular in function (e.g., “politics’ importance,” “the United States’ foreign policy”) and to pluralized versions of names (e.g., “the Johnsons’ car”).

Examples: Apostrophe after “s” for plural possessives
My grandparents’ cat is not very friendly.

All the former principals’ portraits are mounted on the wall.

The apartments’ soundproofing is not very effective.

No apostrophe “s” in possessive pronouns

Unlike possessive nouns, possessive pronouns do not contain apostrophes. The possessive pronouns are mineoursyourshishers, its, theirs, and whose.

It’s important not to add an apostrophe to these words, especially when they can be easily confused with contractions:

  • The cat licks it’s fur. [“it is/has fur”?]
  • The cat licks its fur.
  • I’m not sure who’s this is. [“who is/has this is”?]
  • I’m not sure whose this is.

Other forms such as “our’s,” “your’s,” “her’s,” and “their’s” simply aren’t real words.

Apostrophe “s” as a contraction of “is” or “has”

You’ll also commonly see an apostrophe followed by an “s” used to indicate a contraction of “is” or “has” with the previous word. You can tell which word it’s short for based on the context (e.g., “my car’s [car is] not very fast”; “my car’s [car has] got a few dents”).

“Is” and “has” can be contracted with just about any noun (and with many pronouns), so it’s occasionally difficult to see at first glance whether something is a possessive noun or a contraction. Again, the context of the sentence will make it clear what is intended.

Examples: Contractions vs. possessive apostrophes
My boyfriend’s hobbies [the hobbies of my boyfriend] include chess and hiking.

My boyfriend’s been [boyfriend has been] on many ambitious hikes.

The bike’s handlebars [the handlebars of the bike] seem loose.

The bike’s quieter [bike is quieter] than usual. Did you fix the gears?

As mentioned in the previous section, apostrophes are not used in possessive pronouns, so “who’s” and “it’s” are always contractions, not possessives.

Note
You should avoid contractions in academic writing, where they are considered too informal. Write out phrases in full instead (e.g., “the bike is quieter”). Using possessive nouns is completely fine, though.

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No apostrophe before “s” for plurals

In almost all cases, you should not add an apostrophe before the “s” when you’re simply pluralizing a noun. For example, the plural of “mango” is “mangos,” not “mango’s.”

This common mistake is sometimes called the “grocer’s apostrophe,” based on the fact that you’ll often encounter it on signs in shops and markets.

People are particularly likely to believe an apostrophe is needed when pluralizing nouns ending in vowel sounds (e.g., “frisbee’s”), numbers or decades (e.g., “1980’s”), surnames (e.g., “Jones’s”), or acronyms (e.g., “TV’s”), but the apostrophe is wrong in all of these contexts. The correct forms are “frisbees,” “1980s,” “Joneses,” and “TVs.”

Exception: Pluralizing letters

There is one context in which style guides do advise adding an apostrophe for a plural. This is when you’re pluralizing an individual letter.

In this case, the result of just adding an “s” without any punctuation can often be mistaken for another word (e.g., “is”) or simply look wrong (e.g., “ss”). So it’s standard to add an apostrophe in this context.

Example: Apostrophe “s” to pluralize lowercase letters
There are five s’s and two e’s in “assesses.”

Some style guides instead advise italicizing the letter (but not the following “s”): “two es.”

Worksheet: Possessive apostrophe

Want to test your understanding of when to add an apostrophe “s” and when to add just the apostrophe? Try the worksheet below. In each sentence, fill in the correct possessive noun (ending in ’s or just ) based on the noun presented in brackets.

  1. The [dog] _____ toys haven’t been touched.
  2. Her [parents] _____ house was in the middle of nowhere.
  3. The [children] _____ dinner is almost ready.
  4. This [thesis] _____ main goals are outlined below.
  5. That was [Sergius] ______ idea, not mine.
  1. The dog’s toys haven’t been touched.
  1. Her parents’ house was in the middle of nowhere.
    • To create a possessive from a plural noun like “parents,” you only need to add an apostrophe.
  1. The children’s dinner is almost ready.
    • Although “children” is a plural noun, it’s an irregular one that doesn’t end in “s,” so the “s” is added in this case.
  1. This thesis’s main goals are outlined below.
    • Although “thesis” ends in “s,” it’s a singular noun, so the “s” is still added.
  1. That was Sergius’s/Sergius’ idea, not mine.
    • You can choose whether to add the extra “s” to a singular name ending in “s.” Most style guides recommend adding the “s” consistently, but it’s also acceptable to make the choice based on which version would be easier to pronounce.

Other interesting language articles

If you want to know more about commonly confused words, definitions, common mistakes, and differences between US and UK spellings, make sure to check out some of our other language articles with explanations, examples, and quizzes.

Sources for this article

We strongly encourage students to use sources in their work. You can cite our article (APA Style) or take a deep dive into the articles below.

This Scribbr article

Caulfield, J. (2023, November 27). When to Use Apostrophe S ('s) | Guide & Examples. Scribbr. Retrieved 10 July 2024, from https://www.scribbr.co.uk/english-language/when-to-use-apostrophe-s/

Sources

Butterfield, J. (Ed.). (2015). Fowler’s dictionary of modern English usage (4th ed.). Oxford University Press.

Garner, B. A. (2022). Garner’s modern English usage (5th ed.). Oxford University Press.

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Jack Caulfield

Jack is a Brit based in Amsterdam, with an MA in comparative literature. He writes for Scribbr about his specialist topics: grammar, linguistics, citations, and plagiarism. In his spare time, he reads a lot of books.