Using Possessive 's with Time Phrases
We often use the possessive 's with time phrases. We don't normally think of time being able to own or possess things, but we use these phrases to say that something is associated with a certain period of time.
It is three days' drive to the mountains.
The drive to the mountains will take three days. The drive is associated with the three days.
You need to give one week's notice before you leave.
You must give notice of one week. The notice is associated with the one week.
In general we use possessive 's when we are talking about living things, such as people and animals. We use 'of' when we are talking about inanimate objects. Learn more about using possessive 's.
Singular and Plural Time Phrases
The rules for making time phrases possessive are the same as for other nouns.
For singular time periods, we make the possessive form by adding 's.
one week's notice
one month's salary
For plural time periods that already end in s, you add just the apostrophe (').
two weeks' notice
six months' salary