Round brackets ( )

Round brackets – known as parentheses – allow you to add explanatory or qualifying content to a sentence. They also show mathematical groupings.
Body text
Add secondary content to a sentence
They have completed a feasibility study (see chapter 3).

Common uses of parentheses when adding extra content include:

IntroducingExamples

References, including in
the author–date system

  We must immediately boost our technical capacity (see 2.2).

  The study came to light in 2018 (Blackburn 2019).

Acronyms or initialisms

  The authority acts as a competency standards body (CSB).

Details supporting a 
general statement

  They’ve cut funding ($1.2 million) and jobs (25 part-time).

Comparative data

  Domestic travel cost $65,000 in 2019 ($50,000 in 2018).

Secondary detail you
want to de-emphasise

  Our latest tax return was submitted late (due to errors in our IT systems) but we avoided paying any interest. 

But remember that any brackets can disrupt the flow of your text and encourage you to add more detail than you really need. If you’re tempted to bracket long chunks of text, think about:

  • splitting your sentence into 2
  • rephrasing the text with other punctuation, such as commas
  • trimming or deleting the bracketed text altogether.
Our event on 25 September was a great success. We were delighted to see so many business leaders, from manufacturers to bankers, at the art gallery.
The event (held at the art gallery on 25 September) was a great success and we were delighted to see so many business leaders from all sectors (including manufacturing, legal, trade, media, and banking and investment) in attendance.
Equations
Group numbers to show the order of operations
x = 2(3y + 4z)
Use round brackets in an equation to show the calculations that need to be done first.
5 x (32 + 6) = 190
5 x 32 + 8 = 168

If the equation is very complex, you might need to pair round brackets with square ones.

[(7 + 3) x (4 – 1) x 5] = 150
7 + 3 x 4 – 1 x 5 = 14
Surrounding punctuation
Place commas and full stops carefully

Placing a comma before a set of brackets is not necessary. You can put 1 after the closing bracket, if the text that follows starts a new independent clause. If a bracket contains a non-restrictive element within a single clause, do not add any commas.

If you receive home care services (through a registered provider), your family may be eligible for a one-off government assistance payment.
Land clearance rates (already at record levels) have increased again this year.

When the bracketed text falls at the end of the sentence, you usually put the full stop outside the closing bracket. Only include it inside the brackets if the bracketed text stands alone as a sentence.

Gold Bank was awarded ‘Bank of the year’ for 2019 (runner-up in 2018).
Please visit the Bluewater branch. (We are open Monday to Friday during business hours.)
See also:   Brackets ( ) [ ] < > { },  In-text citations,  Mathematical symbols