The Oxford Comma
The Quick AnswerAn Oxford Comma is a comma used before the last list item in a list of three or more items.
With two items in a list, don't use a comma to separate the list items (unless it helps your reader). When there are three or more list items, then those following "US convention" should use a comma (often called an Oxford Comma) with the conjunction (usually and or or).
- Bacon, eggs, and tomatoes ()
- Bacon, eggs and tomatoes ()
A Page Dedicated to the Oxford CommaShould you put a comma before and? I really wish that were a yes/no question. Unfortunately, it's not.
The aim of this page is to answer that question for you and to introduce you to the Oxford Comma. Be aware that some people would happily start a fight with you for not using an Oxford Comma while others find the Oxford Comma a complete waste of printer ink.
A Comma with Two List ItemsThe whole world agrees that when there are two single-word items in a list, there is no need to use a comma before the and (called a coordinate conjunction). For example:
- Bacon and eggs
- The Bakerloo line runs between Harrow and Wealdstone and Elephant and Castle.
- The Bakerloo line runs between Harrow and Wealdstone, and Elephant and Castle.
Let's look at another example:
- There are delays between The Embankment and Elephant and Castle.
- There are delays between The Embankment, and Elephant and Castle.
The Oxford Comma (Three List Items)When there are three or more list items, things start getting a little more complicated because there is no unified position on whether to use a comma with the and before the last list item. For example:
- Bacon, eggs, and tomatoes. () (The comma with the and in this example is the Oxford Comma. This is the convention followed by most (but not all) Americans.)
- Bacon, eggs and tomatoes. () (This is the convention followed by most (but not all) Brits. The most notable exception is the Oxford University Press, after which the Oxford Comma gets its name.)
|Followers of the Oxford Comma
|Avoiders of the Oxford Comma|
Does the Oxford Comma Eliminate Ambiguity?The Oxford Comma is useful for showing the separations between the list items. For example:
- I like to have a mug of tea, bacon and eggs and toast.
- A mug of tea.
- Bacon and eggs.
- A mug of tea.
- Eggs and toast.
- I like to have a mug of tea, bacon and eggs, and toast.
- Jack left the pub with John (a policeman) and Simon.
- Jack left the pub with John, a policeman, and Simon.
Be aware though that not using an Oxford Comma can also introduce ambiguity for the same reason. Look at these two sentences:
- Jack left the pub with the twins (Sarah and Janet).
- Jack left the pub with the twins, Sarah and Janet.
Clarity Trumps Convention Every Single TimeSo, there are arguments for and against the Oxford Comma. As it happens, you probably don't have a choice whether to adopt the Oxford Comma or not. If you live in the UK, you probably shouldn't adopt it. If you live in the US, you probably should. Whatever convention you go for, be consistent. That is the only rule.
This is not a 100% rule, however. If your local convention means putting ambiguity into your writing, then break the convention to eliminate the ambiguity.
There is only one 100% rule when it comes to the Oxford Comma:
Clarity trumps convention.
An Infographic about Ambiguity with and without the Oxford Comma
Sometimes the Oxford Comma creates ambiguity. Sometimes it eliminates it. The same is true for not using an Oxford Comma.