Commas before Conjunctions (e.g., "and," "or," "but")

by Craig Shrives

A Comma before a Conjunction

Words like "and," "or," and "but" are known as coordinating conjunctions. (There are other coordinating conjunctions, but these three are by far the most common.)

The rules for using a comma before a conjunction like "and," "or," and "but" are not simple because it depends how the conjunction is being used and what writing convention you're following.

Let's start with a rule that everybody agrees on: Use a comma before a conjunction that joins two independent clauses (an independent clause is a clause that could stand alone as a sentence). For example:
He is a great swimmer
+
, but
+
he prefers to play golf.


Notice that both halves of this sentence could be standalone sentences. Each half is an independent clause.
  • He is a great swimmer.
  • (This works as its own sentence.)
  • He prefers to play golf.
  • (This also works as its own sentence.)
When a conjunction joins two standalone "sentences" (i.e., independent clauses), a comma is required before the conjunction (in this example, the conjunction is "but").

Another Example of a Conjunction Joining Two Independent Clauses

  • I may consider your plan, or I may disregard it.
Let's look at this sentence again:
I may consider your plan
+
, or
+
I may disregard it.


Both halves are independent clauses. Therefore, a comma is required before the conjunction "or."

A More Complicated Example

Here is a slightly more complicated example:
  • Applicants must be able to tell jokes and sing, and they must be able to dance.
  • (NB: The first "and" is just a conjunction in a list.)
Let's look at this sentence again:
Applicants must be able to tell jokes and sing
+
, and
+
they must be able to dance.


This is two independent clauses joined by the conjunction "and." Therefore, a comma is required before "and."

Not an Example of a Conjunction Joining Two Independent Clauses

This sentence does not contain two independent clauses:
  • Applicants must be able to sing and be classically trained dancers.
  • (In this example, the conjunction "and" is not joining two independent clauses. Therefore, a comma is not required after "sing." The phrase "be classically trained dancers" cannot stand alone as a sentence. Therefore, it is not an independent clause.)

Some Real-Life Examples

Here are some real-life examples with commas used correctly before conjunctions:
  • A little dog can start a hare, but it takes a big one to catch it.
  • Basically my wife was immature. I'd be at home in my bath, and she'd come in and sink my boats. (Actor Woody Allen)
  • The play was a great success, but the audience was a disaster. (Playwright Oscar Wilde)
  • We make a living by what we get, but we make a life by what we give. (British Prime Minister Winston Churchill)
This example is wrong. There should be a comma before the "and."
  • Drink is the curse of the land. It makes you fight with your neighbor. It makes you shoot at your landlord and it makes you miss him. (Well-cited Irish quotation by anon)
  • ("It makes you shoot at your landlord" and "It makes you miss him" are independent clauses. Therefore, a comma required before "and.")

No Comma Necessary for Short Clauses

Be aware that if the two "sentences" (i.e., the independent clauses) are very short, it is acceptable – for style purposes – to omit the comma.
  • Craig joined the Army and Darren joined the Marines.
  • Craig joined the Army, and Darren joined the Marines.
  • (Both versions are acceptable.)

An Infographic about Using a Comma before a Conjunction

Here is an infographic summarizing the use of a comma with a conjunction that joins two independent clauses:
commas before conjunctions like 'and,' 'but,' and 'or'

Too Many Commas? Use a Semicolon

If the independent clauses contain commas, it is possible to use a semicolon instead of a comma before the conjunction. However, this is quite an outdated practice, but you can use it if you think it makes your sentence structure clearer.
  • Last year, PLC provided the material; and we, L&S Ltd, built the road.
  • (Here, the author has used a semicolon (instead of a comma) before "and" because the independent clauses have their own commas. This is acceptable for clarity, but it's an old-fashioned writing style.)
Read more about using semicolons before conjunctions.

Using a Comma before a Conjunction in a List

Don't Use a Comma to Join Two List Items

Here is another rule that everyone agrees on: Do not use a comma before a conjunction that joins two list items. For example:
  • Burger and fries
  • She would only drink water and wine.
  • We have never been to Europe, or Asia.
  • (With two list items, there is no need for the comma.)

The Rules with Three List Items

When there are three or more list items, things get complicated because there are two conventions. As a general observation, those following US writing conventions use a comma before the conjunction in a list of three or more things, but those following UK writing conventions do not. For example:
  • burger, shake, and fries ()
  • burger, shake and fries ()
  • burger, shake and fries ()
  • We have never been to Europe, Asia, or South America. ()
  • We have never been to Europe, Asia or South America. ()
  • We have never been to Europe, Asia or South America. ()
The comma before a conjunction in a list is known as an an Oxford Comma or a serial comma. Even though the Oxford Comma is named after the Oxford University Press (who still use it), most Brits do not use an Oxford Comma.

Read more about commas in lists.
Read more about the Oxford Comma.
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

Using commas (a summary) Our big commas test What are conjunctions? The Oxford Comma Commas after a sentence introductions Commas after a transitional phrase Commas after interjections (yes, no, indeed) Commas for parenthesis Commas in lists Commas with a long subject Commas with numbers Commas with quotation (speech) marks Commas with the vocative case Commas with Dear, Hello, and Hi