Apostrophes in Time Expressions

homesitemapcommon errors apostrophes in time expressions

The Quick Answer

Apostrophes are used in time expressions. For example:
  • 1 year's insurance correct tick
  • 2 days' leave correct tick
  • a week's pay correct tick
When it is one measure of time (e.g., a day, one week), the apostrophe goes before the "s" (e.g., a day's pay, one week's vacation). When it is more than one measure of time (two days, five weeks), it goes after the "s" (e.g., two days' pay, five weeks' vacation).
apostrophes in time (temporal) expressions

Apostrophes in Time Expressions (Temporal Expressions)

Apostrophes are used in time expressions (e.g., three years' experience, two days' pay, one day's time). These are also known as "temporal expressions."

In a temporal expression, the apostrophe is positioned before the "s" for a single unit of time (e.g., a day) and after for plural unit of time (e.g., two days). For example:
  • I never did a day's work in my life. It was all fun. correct tick (Inventor Thomas A. Edison)
  • (As this is "one day," the apostrophe goes before the "s.")
  • Alan was given two days' notice. correct tick
  • (As this is "two days," the apostrophe goes after the "s.")
  • That is the equivalent of one year's pay. correct tick
  • (As this is "one year," the apostrophe goes before the "s.")
  • My car came with three year's free insurance. wrong cross
  • (As this is "three years," the apostrophe should go after the "s.")

Imagine the Apostrophe Replaces "Of"

The following do not have any apostrophes in them:
  • I lived in Africa for 3 years. correct tick
  • She has six months left to run on her loan. correct tick
This point causes confusion among many. As a rule, you should only use an apostrophe in an expression where the word "of" might have been used. For example:
  • six months' insurance correct tick
  • (six months of insurance)
  • a day's leave correct tick
  • (a day of leave)
  • She has six months' left to run on her loan. wrong cross
  • (She has six months of left to run on her loan.)
    (This is nonsense. It's wrong.)
  • She has six months left to run on her loan. correct tick
  • (This is correct with no apostrophe.)

It's Not Always about Time

The vast majority of these expressions are time expressions, but some relate to value and distance too:
  • 10 pounds' worth of potatoes and 1 pound's worth of onions correct tick
  • a stone's throw away correct tick

Real-life Examples of Temporal Expressions

Here are some extracts from newspapers:
These are both correct. correct examples of temporal expressions
This is wrong. It should be "3 months' mobile insurance." incorrect example of temporal expression
This is wrong. It should be "4 years' free credit." incorrect example of temporal expression, missing apostrophe

Learn about Apostrophe Placement in Temporal Expressions

Play around with this widget to learn more about apostrophe placement with temporal expressions:

This widget is in Learning Mode.
Singular Getting ready... Getting ready...
Plural Getting ready...
Getting ready...
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This page was written by Craig Shrives.

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