Oxford Comma

by Craig Shrives

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What Is an Oxford Comma?

An Oxford Comma is a comma used before the conjunction (usually "and") in a list of three or more items. For example:
Oxford Comma definition

Who Uses the Oxford Comma?

Most US writers use the Oxford Comma. For example:
  • Burger, fries, and a shake ()
  • (This is how about 85% of US writers would punctuate this sentence. The remainder would not put a comma before "and.")
Most writers in the UK do not use the Oxford Comma. For example:
  • Fish, chips and peas ()
  • (This is how about 60% of UK writers would punctuate this sentence. The remainder would put a comma before "and.")

Take our "Oxford Comma" Poll

Do you use the Oxford Comma? Let us know by taking our poll.
Regardless of whether you follow the so-called US or UK convention, be prepared to break the convention if there's ambiguity in your sentence. There is only one 100% rule with the Oxford Comma: Clarity trumps both conventions.

A Hot Topic!

  • 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 or screen pixels.

More about the Oxford Comma

Writers often ask whether they should put a comma before "and." I really wish that were a yes/no question. Unfortunately, it's not.

A Comma with Two List Items

The 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 coordinating conjunction). For example:
  • Bacon and eggs
However, when the list items are longer (NB: We're still talking about two list items at this stage) and especially when they include the word "and," there is a debate on whether you should use a comma. In other words, which version below should we write?
  • The Bakerloo line runs between Harrow and Wealdstone and Elephant and Castle.
  • The Bakerloo line runs between Harrow and Wealdstone, and Elephant and Castle.
Remember that it is okay to use a comma before the "and" if it eliminates ambiguity or simply helps your reader to spot the list items more easily. Therefore, the second version above is the most appropriate.

Let's look at another example:
  • There are delays between The Embankment and Elephant and Castle.
This could be ambiguous. Are the delays between "The Embankment and Elephant" and "Castle," or are the delays between "The Embankment" and "Elephant and Castle"? A comma would eliminate the ambiguity. For example:
  • There are delays between The Embankment, and Elephant and Castle.
NB: At this point, we're not talking about the Oxford Comma. We're just talking about a clarity issue. The Oxford Comma is a comma used when there are three or more list items.

The Oxford Comma (Three or More List Items)

When there are three or more list items, things are 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.)
You should follow whatever convention your company follows. If you don't have a company convention, then copy the convention used in a decent national newspaper. If you're free to make your own mind up, then pick a convention and be consistent. That is the golden rule.

A Summary of the Oxford Comma

In summary:
Followers of the Oxford Comma
(generally Americans)
  • I visited New York and London.
  • (There is no need for a comma with just two list items.)
  • I visited New York, Paris, and London.
  • I visited New York, Paris and London.
Avoiders of the Oxford Comma
(generally Brits)
  • I visited New York and London.
  • (There is no need for a comma with just two list items.)
  • I visited New York, Paris, and London.
  • I visited New York, Paris and London.

Does the Oxford Comma Eliminate Ambiguity?

The Oxford Comma Is a Good Separator

The Oxford Comma is useful for showing the separations between the list items. Look at this example without an Oxford Comma:
  • I like to have a mug of tea, bacon and eggs and toast.
Without an Oxford Comma, it is unclear whether the list represents:
Possibility 1:
  • A mug of tea
  • Bacon and eggs
  • Toast
  • or Possibility 2:
  • A mug of tea
  • Bacon
  • Eggs and toast
  • However, with an Oxford Comma, there is no ambiguity:
    • I like to have a mug of tea, bacon and eggs, and toast.
    • (This must be "Possibility 1.")

    The Oxford Comma Can Cause Ambiguity

    The downside of the Oxford Comma is that it can sometimes introduce ambiguity because commas can be used as parenthetical punctuation, i.e., like parentheses (i.e., round brackets). Look at these two sentences:
    • Jack left the pub with John (a policeman) and Simon.
    • Jack left the pub with John, a policeman, and Simon.
    Both of the examples above are fine grammatically. However, if you live in a place that uses the Oxford Comma, then you cannot be sure whether the second version relates to two people or three people. It could mean either of the following:
    Two people:
  • A policeman called John
  • Simon
  • or Three people:
  • an unnamed policeman
  • John
  • Simon
  • Without an Oxford Comma, there is no ambiguity:
    • Jack left the pub with John, a policeman and Simon.
    • (This must be three people.)

    The Oxford Comma Can Eliminate Ambiguity

    Also, be aware that failing to use an Oxford Comma can introduce ambiguity. 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.
    Both are fine grammatically. However, if you live in a place that doesn't use the Oxford Comma, then you cannot be sure whether the second version relates to two people or four people.
    Two People
  • twins called Sarah and Janet
  • or Four people
  • unnamed twins
  • Sarah
  • Janet
  • Adding an Oxford Comma, removes the ambiguity:
    • Jack left the pub with the twins, Sarah, and Janet.
    • (This must be four people.)

    Clarity Trumps Convention Every Single Time

    So, 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. 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.
    Oxford Comma ambiguity

    Why Should I Care about the Oxford Comma?

    Be Consistent, But Break Convention for Clarity

    Failing to use, or using, Oxford Commas could annoy your readers if you choose a different convention to them. So, if you're unsure what convention to follow, hunt down a few authoritative local texts and copy whatever convention they use.

    Thinking about the Oxford Comma will help you to keep your text consistent. However, if you write something ambiguous, try to reword your sentence. If that proves too cumbersome, have the confidence to switch conventions in the same document. Above all, remember this: Clarity trumps both conventions.

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    See Also

    Using commas (a summary) Try our commas test Using semicolons in lists Commas after a sentence introductions Commas after a transitional phrase Commas after interjections (yes, no, indeed) Commas before conjunctions (and, or, but) Commas for parenthesis Commas with a long subject Commas with numbers Commas with quotation (speech) marks Commas with the vocative case Commas with Dear, Hello, and Hi

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