Which one is correct?

1: Well, you canceled on Tuesday and our policy is 24 hours' notice for all cancellations.

2: Well, you canceled on Tuesday and our policy is 24 hours notice for all cancellations.

To me personally, the first one makes more sense grammatically. But I've also heard that the second version is how they typically write it on paper forms at hospitals (that's what native speakers say). Could you please clarify my confusion?

  • It seems that you might be interested in the issue that is found in "an hour's delay" versus "a two-hour delay"; this is discussed in H&P's CGEL, page 470, [46], in their subsection "Measure genitives".
    – F.E.
    Commented Jun 23, 2015 at 17:40
  • Possible duplicate of Apostrophes in Time Expressions Commented Jul 2, 2019 at 14:56

4 Answers 4


You are correct. "24 hours' notice" is possessive for the same reason as "a day's drive," "a moment's thought," or "in five minutes' time." I assume the apostrophe is dropped due to simple ignorance.

Expressions involving time with no apostrophe are in use, too, but they take forms like "two-hour meeting," where the hyphen makes a compound adjective. If your example fit that pattern, it would be "24-hour notice," but that would imply a notice that lasted 24 hours, a nonsensical concept. The possessive pattern is a much better fit.

  • To be given 24-hour notice is a common enough expression.
    – Lambie
    Commented Aug 5, 2019 at 22:57

It should be 1, as there is a possessive present. See here for more details: http://www.quickanddirtytips.com/education/grammar/possessives

Also, we can infer that the conversation is about an appointment or meeting, so there is no need to mention this again hence no object in required for cancelled.


Correct would be:

Well, you canceled on Tuesday, and our policy is 24 hours' notice for all cancellations.

You need the apostrophe after hours as well as a comma before and and a period.

This is an example of an inanimate possessive in English. Time is actually an exception in this case. Generally, they're expressed with of (The window of the car, and not the car's window), but time words use an apostrophe for possession. Since it's an uncommon expression, most English speakers will use or write it incorrectly.

I'd recommend using the apostrophe yourself, but be prepared to interpret it if you see it either way.


I am puzzled by this as the answer refers to it being possessive, however my logic tells me that the possession is with the appointment (or possibly the policy) and not the hours (note I don't put an apostrophe on the word hours here). The fact that the 'appointment' is not mentioned in the phrase means it cannot take possession. In my view the grammatically correct phrase would be:

"Well, you cancelled on Tuesday and our policy requires 24 hours notice for all cancellations"

  • This is the way that feels right to me because "24 hours" notice feels like shorthand for "24 hours OF notice". The notice doesn't belong to the hours. This is a shorter way of asking for notice 24 hours in advance. I'm not confident I'm right, but this is my opinion.
    – KC Baltz
    Commented Sep 22, 2016 at 16:22
  • @KCBaltz "The notice doesn't belong to the hours." correct - the hours belong to the notice, hence the possessive and the apostrophe. Instead of a plurality of hours, instead try the sentence with a singular day: "one day's notice" is correct - "one day notice" would be incorrect. Therefore, "two days' notice" and "xxx hours' notice", etcetera is correct.
    – Aaron F
    Commented Aug 26, 2020 at 21:20

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