Full Stops (Periods) in Abbreviations (Grammar Lesson)

The Quick Answer
Abbreviations can be written with or without full stops (periods ). Often, you have a choice. In other words, you can write C.N.N. or CNN, or e.g. or eg.

Whatever format you use, be consistent. The most common format is to omit full stops/periods in uppercase abbreviations (e.g., CNN) but to use them in lowercase abbreviations (e.g., e.g.).

If the abbreviation is a company name, you should copy the format the company uses.

Full Stops (Periods) in Abbreviations

It is considered untidy to mix abbreviations with full stops and ones without full stops in the same article. The first two examples below are both correct because the writer has been consistent.

  • The band travelled around UK and USA last year.
  • The band travelled around U.K. and U.S.A. last year.
  • It was only shown on ITV and not B.B.C.
  • (This is an inconsistent use of full stops (periods). It is considered untidy.)
  • The M.D. insisted that his PA had left by 4 o'clock.
  • (Untidy)

The Tendency: Do Not Use Full Stops / Period in Uppercase Abbreviations but Use Them in Lowercase Abbreviations

Abbreviations made up of capital letters tend not to have full stops, but abbreviations made up of lowercase letters tend to have them. For example:
  • BBC
  • (British Broadcasting Corporation)
  • LRS
  • (Linear Recursive Sequence)
  • CBS
  • (Columbia Broadcasting System)
  • a.m.
  • (ante meridiem - before midday)
  • p.m.
  • (post meridiem - after midday)
  • i.e.
  • (id est - that is)
  • e.g.
  • (exempli gratia - for the sake of an example)
  • p.p.
  • (per procurationem - by the agency of)
Note: This is a tendency not a rule.

If the abbreviation is a company name, copy whatever convention the company uses. For example:
  • Our team was hosted by the Italian club A.S. Livorno Calcio.
  • (A.S. Livorno Calcio is the name shown on the logo and in all correspondence.)
  • The shop will be taken over by the clothing company s.Oliver in June.
  • We will meet at P.F. Chang's in Tokyo.
Note: Do not worry about this point. There are very few companies who use full stops / periods in their names. I mean almost none.

Do Not Use Two Full Stops / Periods If a Sentence Ends with an Abbreviation

If a sentence ends with an abbreviation (including a contraction like etc. ) that ends with a full stop / period, then do not use a full stop / period to show the end of the sentence. However, other end marks (such as question marks, exclamation marks) should be used. For example:
  • I need milk, bread, cheese, etc.
  • She moved from I.T.V. after an irresistible offer from the B.B.C.
  • She moved from I.T.V. after an irresistible offer from the B.B.C..
  • (Logically, this is correct, but it is too unwieldy.)
  • Will she move back to the B.B.C.?
  • (This is correct, but it looks a little scruffy. To avoid this, use BBC instead of B.B.C.)
The only exception to doubling up end marks with full stops / periods is ellipsis (...). For example:
  • Standing tall and with the Lord's Prayer mumbling across our lips, we entered the chamber...."
  • (This ends in four dots: three for the ellipsis and one to end the sentence.)

See Also

Using AD, BC, BCE and CE Full stops (periods) in contractions Forming the plurals of abbreviations