Using Parentheses (Round Brackets)

by Craig Shrives
The Quick Answer

How To Use Parentheses

Parentheses, i.e., round brackets, are used to insert additional information into a text (usually an explanation or an afterthought). For example:
  • John (the team captain) is 6 feet 4 inches tall.
  • (Here, the bracketed text provides an explanation.)
  • I love cakes (provided they're not chocolate).
  • (Here, the bracketed text provides an afterthought.)
Parentheses can also be used to show a plural option alongside a singular option. For example:
  • Remove the pin(s) from the leg.
  • (There might be one pin, but there could be more.)

Punctuation with Parentheses

When parentheses are used to insert information at the end of a sentence, the end punctuation of the sentence is placed outside the bracket. For example:
  • The whole crew survived (even the dog).
When the additional information is a standalone sentence among other sentences, then the whole thing including the end punctuation is placed inside the parentheses. For example:
  • The whole crew survived. (Even the dog survived.)
In a situation where the additional information is a standalone sentence within another sentence, then the end punctuation is usually omitted for readability. For example:
  • The whole crew (The crew was four men and a dog) survived.
  • (Note there is no period (full stop) after "dog.")
using parentheses (round brackets)

Parentheses for Additional Information

Parentheses are used to insert additional information in text. If you were to remove the brackets and the information inside, the text would still work. For example:
  • Set in the 17th century, The Three Musketeers ("Les Trois Mousquetaires" in French) is a novel by Alexandre Dumas.
  • Although they are relatively common off Australia, California, South Africa, and Mexico, great white sharks usually inhabit coastal waters where the water temperature ranges 12-24 degrees Celsius. They generally hunt by detecting the electrical fields (They can detect less than one billionth of a volt) emitted by the movements of their prey.

Parentheses for Singular or Plural Options

For brevity, parentheses can be used to show that a word could be either singular or plural. For example:
  • Please write the name(s) of your guest(s) in the section below.
  • Ensure the rod(s) is(are) aligned with the top section.

Don't Overuse Parentheses

Using lots of parentheses in your writing is usually a sign of bad sentence structure. Parentheses also look a little informal in business correspondence. Luckily, the latter issue is easily solved. You do not have to use parentheses all the time. You have a choice between parentheses, commas, and dashes. These are all types of parenthetical punctuation. The information between a pairing of parenthetical punctuation is called a parenthesis.

How Long Can Parenthesis Be?

Parenthesis is used to add additional information. Often, it is just a few words, but it can be a complete sentence or even a few sentences. (If it's any longer than that, you should probably reconsider whether it's appropriate as a parenthesis.)

Periods (Full Stops) Inside or Outside the Brackets?

In most cases, the period (full stop ) will be outside the end bracket, but if your parenthesis is a complete sentence, it should start with a capital letter and end in a period, which would be inside the brackets.
  • Ashley likes cakes (especially cream cakes).
  • Ashley likes cakes. (He especially likes cream cakes.)
So, it just follows logic. If the information inside the brackets is part of another sentence, treat it as such. If it's a sentence in its own right, treat it as such; i.e., give it its own period inside the parentheses.

If the parenthesis is a complete sentence within another sentence, you can omit the period for style reasons. Look at this example again:
  • Great white sharks usually inhabit coastal waters where the water temperature ranges 12-24 degrees Celsius. They generally hunt by detecting the electrical fields (They can detect less than one billionth of a volt) emitted by the movements of their prey.
  • (Note there is no period after "volt.")
Here is another example:
  • As the wine-growing season in France (We lived in France during my twenties) draws to a close, the festivals start.
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.

See Also

The different types of brackets Punctuation inside or outside quotation marks? Using square brackets More about brackets, commas, and dashes What is parenthetical punctuation? What is a parenthesis?