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Commas before conjunctions (e.g., and, or, but)

The Quick Answer
When a word like and, or, and but (called conjunctions) joins two independent clauses (i.e., clauses that could stand alone as sentences), you should put a comma before it.

Put a Comma before a Conjunction If It Joins Two Independent Clauses

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

(NB: Conjunctions are often used in lists, and the ruling about using a comma before a conjunction in a list depends on whether you're following US or UK writing conventions, or whether you're an advocate of the Oxford Comma.)

This page is about conjunctions that are used to merge two standalone "sentences" (or independent clauses as they're really called) into one using a conjunction. This is a very common practice. When a conjunction is used in this way, it is usual to place a comma before it.

Example of a Two Independent Clauses Being Joined with a Conjunction

  • He is a great swimmer, but he prefers to play golf.
Let's look at this sentence:
"He is a great swimmer"
+
"He prefers to play golf"
The sentence is made up of two standalone "sentences" (i.e., independent clauses). The two "sentences" have been merged into one with the conjunction but. When this happens, a comma is required before but.

Another Example of a Two Independent Clauses Being Joined with a Conjunction

Here is another example:
  • I may consider your plan, or I may disregard it.
Let's look at this sentence:
"I may consider your plan"
+
"I may disregard it"
This is also two independent clauses joined by a conjunction (in this case, or). Therefore, a comma is required before the or.)

A More Complicated Example

Here is a slightly more complicated example:
  • The applicant must be able to tell jokes and sing, and she must be able to dance.
  • (NB: The first and is just a conjunction in a list.)
Let's look at this sentence:
"The applicant must be able to tell jokes and sing"
+
"She 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 Two Independent Clauses Being Joined with a Conjunction

This sentence does not contain two independent clauses:
  • The female applicant must be able to tell jokes, sing and dance. ()
  • The female applicant must be able to tell jokes, sing, and dance. ()
In the example above, the conjunction and is not joining two independent clauses. Therefore, a comma is not required after sing if you're following UK conventions. In the US (or if you're an advocate for the Oxford Comma), then a comma would be expected after sing.)

Read more about commas in lists.

Some Real-Life Examples

  • 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.
  • ("It makes you shoot at your landlord" and "It makes you miss him" are independent clauses. Therefore, a comma required before and.)
  • 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. (Woody Allen)

  • The play was a great success, but the audience was a disaster. (Oscar Wilde)

  • We make a living by what we get, but we make a life by what we give. (Winston Churchill)

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 with And

comma before and
The rules governing whether to use a comma before and get complicated when there are three or more list items.



Read more about using a comma before and.
Interactive Test
 
 
Top Tip

Too Many Commas? Use a Semicolon

When independent clauses containing commas are merged together using a conjunction, it is possible to use a semicolon instead of a comma before the conjunction. However, this is quite an outdated practice. Use it very sparingly — if at all.
  • Last year, PLC provided the material; and we, L&S Ltd, built the road.
  • (Here, we have used a semicolon before and because the independent clauses contained their own commas. This is acceptable for clarity, but quite it's an old-fashioned writing style.)
Read more about using semicolons before conjunctions.