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Dates & times

Centuries and decades

Dates, events and periods

Time of day


Centuries and decades

Numerically described periods are not capitalised:

  • 21st century
  • twenty-first century
  • the nineteen-nineties
  • 1990s with no apostrophe, not 1990's.

The preferred style is to use numerals rather than text.


Dates, events and periods

  • 27 November 1999, not 27th November 1999
  • Monday 27 November 1995 (day, month, year with no punctuation)
  • Antarctic summer 1992–93 (with an 'en' dash, not a hyphen)
  • 1980s or early 2000s
  • '50s and '60s
  • in the twentieth century or in the 20th century, but 19th-century literature
  • semester 1 or first semester
  • semester 1 1996 or the first semester 1996
  • World War I and World War II
  • the Vietnam War and the French Revolution.

Also refer to Time of day.


Time of day

For time spans, use an unspaced en dash for simple spans and a spaced en dash for complex spans. A space between the the number and the abbreviation (am or pm) should be retained. For example:

  • 9–11 am, not 9am – 11am
  • 9.30 am – 3 pm, not 9.30 am – 3.00 pm
  • 10 am - 2 pm, not 10am-2pm

When referring to time of day in prose, use either from/to or between/and in place of the en dash. For example:

The lecture will be held from 9am to 10am on Wednesday.
The seminar takes place between 10am and 4pm on Friday.