Apostrophe S in time expressions explained

The apostrophe S in time expressions confuses many English learners, and this lesson shows you exactly when to place it before or after the S. If you have ever hesitated between one week's vacation and five years' experience, this guide is for you.

Everything starts with a single line from Emily in the script: "You should give yourselves one week's vacation and discuss these things calmly." That tiny apostrophe carries a rule worth mastering.

What are time expressions and why do they need an apostrophe?

Time expressions are simply words that relate to time, like week, month, or year. When you connect them to a noun, English asks you to use the apostrophe S [1:44].

Think of phrases like one week's notice or one year's experience. The apostrophe is not optional here, it signals a possessive relationship between the period of time and the noun that follows.

Why do we say "one week's vacation" and not "one week vacation"? Because time expressions in English take a possessive apostrophe. The week "owns" the vacation, so you write week's with an apostrophe before the S.

Where does the apostrophe go, before or after the S?

The placement depends on one thing: whether your period of time is singular or plural. This is the core rule of the whole lesson [2:07].

If the period of time is singular, the apostrophe goes before the S:

• One week's notice.
• One month's holiday.
• One year's experience.

If the period of time is plural, the apostrophe goes after the S:

• Three weeks' notice.
• Four months' holiday.
• Five weeks' experience.

And here is a relief for your speaking: pronunciation does not change [2:33]. Whether the apostrophe sits before or after the S, you say the word the same way. The apostrophe is a written signal, not a spoken one.

Can I replace the apostrophe with the word of?

Yes, and this is a handy escape route if apostrophes make you nervous. You can swap the apostrophe for the word of [2:41].

Look at how both versions carry the same meaning:

• I have five years' experience or I have five years of experience.
• I had two months' vacation or I had two months of vacation.
• She only gave me two weeks' notice or She only gave me two weeks of notice.

But there is a catch. If you decide not to use of, then you must use the apostrophe [3:20]. You cannot drop both. One of them has to appear.

Is "five years experience" correct without an apostrophe? No. You either write five years' experience with the apostrophe or five years of experience with the word of. Skipping both is a mistake.

How can I practice apostrophe S with real examples?

The lesson turns into a game where you earn one point per correct answer [3:30]. All the options sound identical, so your only clue is the singular or plural logic.

Here are the answers worked through:

• The first item is correct with option A.
• Five years' free credit is plural, so the apostrophe goes after the S, which makes B correct.
• In the quote "I may go mad in several years' time," the word several is plural, so C is correct.

Notice the trick with several. Because it always refers to more than one, it behaves as plural, so the apostrophe lands after the S [5:00].

What should I write to reinforce the rule?

After the game, you build your own sentences using these phrases [5:16]:

• Six weeks' holiday.
• One year's insurance.
• Several months' confinement.

Each phrase tests the same instinct: spot whether the time period is singular or plural, then place the apostrophe accordingly.

One quick tip before you practice on your own. Ask yourself "is this one unit of time or more than one?" and the apostrophe will fall into place naturally.

How many points did you get in the exercise? Share your sentences and your score in the discussion panel, and get ready for the next lesson where do, does, and did work as placeholders.