Grammar Monster
Grammar Monster

Using Parentheses (Round and Square Brackets)

The Quick Answer
This page offers an explanation on the correct use of parentheses (round brackets) and square brackets and gives examples of parentheses and square brackets used in sentences.

Round brackets (parentheses) are used:
  • To insert extra information (often an afterthought, clarification, or expansion of a recently mentioned idea).
  • To present a plural option with a singular one, e.g., Your guest(s) must leave before midnight.
Square brackets are used:
  • To make quoted text clearer by expanding on or replacing part of the quote.
  • To make it clear that terms like [sic] and [...] are insertions by the current author not the originator.

Using Round Brackets (Parentheses)

Round brackets are mostly used for inserting additional information into text. The additional information is usually an afterthought or an expansion or clarification of something recently mentioned. The big question with brackets is where to put the end punctuation. Does it go inside or outside the brackets? (There is more on that below and in this lesson on using round brackets.)

For brevity, round brackets can be used to show a plural option alongside a singular one. For example:
  • Do not remove the pin(s) while the light is on.

Using Round Brackets for Additional Information

Round brackets can be used to insert an afterthought or to expand or clarify something nearby (usually the text immediately preceding). Although the most common type of parentheses, brackets are just one of the choices of parentheses. Commas and dashes can also be used. The advantage of using brackets is they are easy to spot. The disadvantage is they tend to make writing look a little informal. Brackets and the information inside can usually be removed from the text without any loss of meaning.

When using brackets, the positioning of end punctuation (usually a period / full stop ) follows logic. For example:
  • She will ride a pony (but not a Dartmoor pony).
  • In this example, the end punctuation belongs to the main sentence not to the parenthesis, i.e., the bit in brackets.
  • She will ride a pony. (However, she will not ride a Dartmoor pony.)
  • In this example, the end punctuation belongs to the parenthesis.
  • She will ride a pony (She told me yesterday) but not a Dartmoor pony.
  • In this example, the parenthesis is a standalone sentence within another sentence. When this happens, for readability, it is okay to omit the end punctuation.

Using Round Brackets to Denote Singular or Plural

For brevity, round brackets can be used to show a plural option. For example, instead of writing your guest or guests, it is possible to write your guest(s). More examples:
  • Remove the sheet(s) so the air can flow freely
  • Please append the name of your guest(s) to the list.
Read more on using round brackets

Using Square Brackets

Square brackets [ ] are usually used to make a quoted text more understandable. They are used to either explain or replace words within a quotation.

Also, square brackets are used with the term [sic] to show the text is how the original author wrote it. They are also used with ellipsis [] to show that some text has been removed.

Using Square Brackets to Make the Text Clearer

Square brackets can be used to add explanatory information to a quotation. For example:
  • If you don't like them [my principles], well, I have others.
They can also be used to replace parts of a quotation to make it clearer. For example:
  • If you don't like [my principles], well, I have others.

Using Square Brackets with [sic]

The term "[sic]" (which comes from the Latin sic erat scriptum, meaning thus was it written) is often seen with square brackets. It is used to show that the text written is the work of the original author. For example:
  • In your statement, you wrote: "I appraised [sic] him of the situation at about 4 o'clock."
  • (In this example, the writer is using [sic] to show that the word appraised was used by the original author. Obviously, it should have been apprised, not appraised. The term [sic] is often used to show a grammar error in quoted text was the originator's mistake and not the quoter's.)

Using Square Brackets with [...]

Ellipsis (three dots) are often written with square brackets. It is used to show that text has been omitted. Compare these two quotes:
  • I don't want any yes-men around me. I want everybody to tell me the truth even if it costs them their jobs.
  • I don't want any yes-men around me [] even if it costs them their jobs.
Read more on using square brackets

A Video on Using Square Brackets

Here is a video summarizing the section on square brackets:

Top Tip

You Can Use Brackets, Commas, or Dashes

Even though they are useful for introducing information to make your writing clearer, round brackets can make your work look a little informal or disorganised. In formal correspondence, you should try to limit their use. Don't forget though, brackets are just one type of parentheses. Commas and dashes are options too. For example:
  • Fingers (real name Simon Betts) was caught after he locked himself in the safe.
  • Fingers, real name Simon Betts, was caught...
  • Fingers — real name Simon Betts — was caught...
Here is a lesson on choice of parentheses.