The 24 hour clock should be used, with the hour separated from the minutes by a full stop. The abbreviations ‘am’ and ‘pm’ should not be used with the 24 hour clock.

For example:

  • The event begins at 11.00 and finishes at 15.00.
  • From 18.00 to 20.30, a drinks reception will be held in the Queen’s Tower Rooms.


Dates should appear before the month, and ordinals (st, nd, rd, th) should not be used.

There is no need to precede a date with the word ‘the’.

Days are generally not included in written dates, and the year should only be included when necessary for clarity or to avoid ambiguity.

For example:

  • Professor Terry Rudolph’s inaugural lecture was held on 29 October 2014.
  • The 2017 Imperial Festival will take place on 6 and 7 May.

Spans of numbers, dates and times

To describe a period of time in prose, ‘from’ and ‘to’ should generally be used, with no dash. ‘Starts/begins at’ and ‘ends/finishes at’ can also be used in this context, as can ‘between’ and ‘and’.

In an advert, list, or where space is limited, start and end times for a period of time can be separated by an en dash (–).

If you are writing about an academic or financial year, separate the two years using an en dash and abbreviate to the minimum number span, for instance: 2020–21 and 2022–23.

To refer to a span of years, an en dash or the words ‘from’ and ‘to’ are acceptable.

When referring to centuries, it is preferable to spell out the word. When referring to decades, numerals or the spelled word can be used, as long as there is consistency throughout a piece of writing. Note that an apostrophe should not be used when referring to a decade using numerals (for example: 1980’s)

For example:

  • Imperial’s June Open Day begins at 10.00 and finishes at 16.30.
  • Careers advisors are on hand to offer guidance between 10.30 and 12.30 every Tuesday.
  • The College’s 2013–14 Annual Report and Accounts was published in December 2014.
  • During the war of 1914–18, many of the College’s buildings in South Kensington were used for war billeting of soldiers and military work.
  • (Poster) Inaugural lecture: Tuesday 7 April, 18.00–20.00.
  • Imperial’s South Kensington Campus has its origins in Prince Albert’s nineteenth-century vision of a quarter dedicated to education and culture.
  • At the end of the 1980s, the College’s merger with St Mary’s Hospital Medical School led to the formation of the Imperial College of Science, Technology and Medicine.