Apostrophe after S

This page is about when to use an apostrophe after the letter s.

If you're a native English speaker, you probably already use apostrophes to show possession. For example:

• The hamster's cage.
• The hamsters' cage.

The question everyone asks with an apostrophe used for possession is where to put the apostrophe. Does it go before the letter s or after the letter s?

Here's the rule (using the example above):

If there is one hamster, the apostrophe goes before the s.
If there is more than one hamster, the apostrophe goes after the s.

What Is the Possessor?

In the examples above, the hamster (or hamster) is called the possessor. The possessor is the "owner" of whatever follows. (Be aware that the word owner is used very loosely. Possessive apostrophes do not always denote possession or ownership.) Here is the rule again using the proper terms:

When the possessor is singular, the apostrophe goes before the s.
When the possessor is plural, the apostrophe goes after the s.

Note: The number of things being possessed is irrelevant. For example:

• The hamster's cage.
(one hamster, one cage)
• The hamster's cages.
(one hamster, lot of cages)
• The hamsters' cage.
(lots of hamsters, one cage)
• The hamsters' cages.
(lots of hamsters, lots of cages)

Only the number of hamsters matters. The number of cages is irrelevant.