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A guide to apostrophe rules

Jessica Malnik

Jessica Malnik

Sometimes, grammar can be confusing. Case in point: figuring out how and when to use an apostrophe.

Apostrophes can signal possessives or contractions. With these two very different use cases, it’s easy to see all of the common mistakes that both adults and children make in using them. That’s why we’ve made this guide as a quick reference to help you out.

In this guide, we explain when you should use an apostrophe, the different types of apostrophes, and how to use them correctly.

When should you use an apostrophe? 

An apostrophe is typically used to show possession or to form a contraction. Apostrophes can be used to form plurals and can also be used as part of a holiday or date — for instance, April Fools’ Day or the ’70s. Many rules go with apostrophe use and multiple ways that they can be used.

Here are some of the most common instances when you should use an apostrophe.

What are the different types of apostrophes? 

The use of apostrophes can be grouped into three different types:

  1. Apostrophes used to show the omission of letters or numbers
    In contractions where one or more letters or numbers are taken out, an apostrophe can be inserted. For example, “she couldn’t go outside.”
  1. Apostrophes used to indicate possession
    Apostrophes can be used to show possession, such as joint possession. They can be used with possessive nouns. For example, “the student’s book.”
  1. Apostrophes used to form plurals (numbers, abbreviations, and symbols)
    Apostrophes aren’t typically used to create a plural. However, there are exceptions for forming plurals of numbers, abbreviations, and symbols. For instance, “there are two 7’s in her number.”

When to not use an apostrophe 

Keep in mind that just as there are rules for instances to use apostrophes, there are also instances where you should not use an apostrophe. 

For example, you shouldn’t use an apostrophe for possessive pronouns.

The following possessive pronouns should not include an apostrophe: her, his, its, my, ours, and yours. Its can be a tricky one to remember if it needs an apostrophe or not. It’s with an apostrophe indicates a contraction — combining the words “it” and “is”. However, used as a possessive pronoun, its doesn’t need an apostrophe. For example, “The bike was in its place in the garage.”

Examples of using the apostrophe 

As mentioned above, apostrophes follow certain rules. Here are the rules for apostrophes and some examples of the correct and incorrect uses of an apostrophe for each.

RULE 1: Use an apostrophe for contractions. The apostrophe in a contraction is placed where letters have been removed from the word. Contractions can make your writing sound more conversational. 

Example 1

Correct: She doesn’t need to go into town. Incorrect: He does’nt think he misplaced the keys.

Example 2

Correct: You can’t reach her on that line. Incorrect: Dont’ tell me what to do. 

Note that contractions should not be used in formal writing. Spell out the words instead of omitting letters and adding an apostrophe. In this next example, though the apostrophe is in the correct place, the writing is a formal piece and should not use contractions.

Example 3

Correct: Researchers have not concluded the experiment. Incorrect: According to the law, you can’t own tigers in the city. (an’t should be spelled cannot for formal writing.)

RULE 2: Use an apostrophe to indicate possession.

For a singular noun, simply add the apostrophe before the letter s

Example 4

Correct: The cat’s toy is in the kitchen. Incorrect: Darcys’ book fell under her desk.

If a noun ends in an s already, then the typical practice for common nouns is to place the apostrophe after the s and another s at the end. However, proper nouns do not include an extra s after the apostrophe.

Example 5

Correct: Mr. Rogers’ shoes are in the closet. Incorrect: Ms. Williams’s car is parked out front.

Example 6

Correct: The bus’s tire was flat. Incorrect: The cactus’ watering can is missing.

When you need to show possession of plurals that don’t end in s, you would simply add an apostrophe and an s following the apostrophe. Here’s how.

Example 7

Correct: We found the deer’s hiding place when we followed their tracks. Incorrect: The childrens’s shirts are in the drawer.However, when you have a plural that ends in an s, you don’t add an s after the apostrophe.

Example 8

Correct: The kittens’ bed was nice and warm. Incorrect: The wolves’s den is by the river.

Example 9

Correct: The kids' show starts at noon. Incorrect: The kids’s lost their soccer game.

When something belongs to more than one person, you should only add the apostrophe to the final name, no matter how many names are listed.

Example 10

Correct: Jack, Lin, and Teagan’s class starts soon. Incorrect: Tony’s and Johnnie’s cousin is visiting this weekend.

If there are separate objects involved that belong to different people in the list, then you can add an apostrophe for each.

Example 11

Correct: Michael’s and Luna’s dogs are playing together. (In this case, Michael and Luna each have a dog that belongs to them.) Incorrect: Juan and Mark’s professors were at the open house. (In this case, Juan and Mark have different professors attending, so Juan should include an apostrophe.)

RULE 3: Use an apostrophe to form specific plurals such as numbers, abbreviations, and symbols.

For double-digit numbers, the apostrophe isn’t necessary. For single digits, both with or without an apostrophe are accepted.

Example 12

Correct: Mariel was born in the '80. Incorrect: Abdul started college in the 1990’s.

Example 13

Correct: You need to add three 8s to the number. ALSO Correct: Her student ID ends in four 5’s.

The best way to improve your grammar skills is to practice, and to use Writer for helpful suggestions. Start a free trial today. Keep writing, and you’ll start to get the hang of when to use apostrophes and when to leave them out.