Apostrophes in time (temporal) expressions
 
Apostrophes are used in time expressions such as 2 days' leave.

When it is one measure of time, the apostrophe goes before the s (e.g., one day's pay). When it is more than one measure of time, it goes afterwards (e.g., two days' pay).
 

Apostrophes in Time (Temporal) Expressions

Apostrophes are used in time expressions such as 3 years' insurance (also called temporal expressions). In a temporal expression, the apostrophe is positioned before the s for single units of time and after for multiple units of time.

Examples:

  • I never did a day's work in my life. It was all fun. (Thomas A. Edison)
  • (one day - apostrophe before the s)

  • Alan was given one day's notice.
  • (one day - apostrophe before the s)

  • That is the equivalent of one year's pay.
  • (one year - apostrophe before the s)

    My car came with a years' free insurance.  [correct the example]
    (one year - apostrophe should be before the s)


    • There is six months' interest-free credit on all sofas.
    • (six months - apostrophe after the s)

    These are both correct.
    (newspaper clipping)


    This is wrong.  It should be 3 months' mobile insurance.
    (newspaper clipping)


    This is wrong. It should be 4 years' free credit.
    (newspaper clipping)

    Applicants should have at least 3 year's experience.  [correct the example]
    (three years - apostrophe should be after the s)

     
     
     
    DO NOT USE APOSTROPHES FOR ALL TIME EXPRESSIONS – ONLY WHEN THEY COULD REPLACE THE WORD OF

    The following do not have any apostrophes in them:

    • I lived in Africa for 3 years.
    • She has six months left to run on her
      loan.
    This point causes confusion amongst 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 (six months of insurance)
    • a day's leave (a day of leave)
    • She has six months' left to run on her loan.
    • (She has six months of left to run on her loan.) (This is nonsense. It's wrong.)
     
     
    IT'S NOT ALL 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
    • a stone's throw away
     


    See also:

    Using apostophes
    The apostrophe error with plurals
    Apostrophes replace letters
    Apostrophes to show the plural of abbreviations
    Apostrophes show possession


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