The Remedy of the Week: Five years time or five years' time?

Each week proofreader Hannah Jones discusses and offers a remedy to common problems we encounter when writing. Today she demonstrates the use of apostrophes with time periods.

A common stumbling block for many writers is whether to use an apostrophe in phrases such as five years time/five year's time. Which is the correct usage?

An apostrophe should be used in phrases where a time period modifies a noun (e.g. notice):

two weeks' notice

a month's holiday

five years' time

Note that, just as in possessive constructions, the apostrophe comes before the s for singular nouns and after the s for plural nouns:

a day's work (singular)

20 years' experience (plural)

However, an apostrophe is not used when a time period is modifying an adjective (e.g. old):

80 years old

five days long

six months pregnant

Hannah Jones is a professional freelance proofreader and owner of The Remedy of Errors.

Visit her website at The Remedy of Errors. She can also be found on Twitter @remedyoferrorsFacebook and LinkedIn.