Commas in Lists

Using Commas in Lists

Commas are used to separate list items when there are more than two list items. For example:

• apples, pears, and bananas
(When there are more than two list items, commas are used to separate them.)
• apples and pears
(There is no comma with two list items.)

There's an issue though. Not everyone follows the same format. Look at this example:

• apples, pears and bananas
(In this example, there is no comma before "and." This style is more popular in the UK than in the US.)

More about Commas in Lists

Commas with Two List Items

When there are two items in a list, don't use a comma to separate the list items (unless it helps your reader). For example:

• Please buy bread and milk.
• Please buy custard, and banana muffins.
(Without the comma, "custard and banana muffins" could be one item. The comma helps the reader.)

Commas with More Than Two List Items

If there are more than two list items, those following US convention should use a comma before the conjunction (usually "and" or "or").

• Please buy bread, milk, and cheese ()

Those following UK convention should not use a comma.

• Please buy bread, milk and cheese ()

Be aware that many in the UK use a comma, which is called a serial comma or an Oxford Comma. If your organization uses the Oxford Comma, you should too. Whatever convention you use, be consistent.

Break the Rule for Clarity

If breaking your "national" convention makes the text clearer (and that could mean omitting or inserting the comma depending on which convention you're following), then break convention. Clarity trumps both conventions. (There's more on this below.)

Printable and Sendable Test

The Oxford Comma

When a comma is used before the conjunction in a list, it is known as an Oxford Comma. Some people (mostly, but not exclusively, Brits) consider the Oxford Comma to be a waste of ink, while others (mostly, but not exclusively, Americans) strongly campaign for its inclusion. There really is no rule. 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!

• Bread, milk and cheese
(This is correct for Brits and those who don't use the Oxford Comma.)
• Bread, milk, and cheese
(This is correct for Americans and those who do use the Oxford Comma.)
• London, Paris and New York
(This is correct for Brits and those who don't use the Oxford Comma.)
• London, Paris and New York
(This is correct for Americans and those who do use the Oxford Comma.)

Summary of Commas in Lists

This table summarizes how commas are used in lists:

Followers of the Oxford Comma (generally Americans)	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.	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.

Break Convention for Clarity

There is another consideration. Sometimes, it is appropriate to break whatever convention you're following for the sake of clarity — even in a list with just two list items. For example:

• The news will be shown after Dangermouse, and Rug Rats.
(Without the comma, people could think that "Dangermouse and Rug Rats" is one programme.)
• The emblem is an amalgamation of the British and Irish flags, the Stars and Stripes, and the Hammer and Sickle.
(Those who don't use the Oxford Comma would normally omit the comma before the highlighted "and" in this example. However, the word "and" appears lots of times. The comma before the highlighted "and" makes it easier for the reader to identify the last list item.)

Beware of Creating Ambiguity with Your Comma

Commas can be used to introduce additional information (called parenthesis). For example:

• My friend, Simon, joined the circus as a clown.
(In this example, commas are being used to add information about "my friend.")

So, when a comma is used before a conjunction in a list, it could make the list item before the comma look like a parenthesis. This could create ambiguity. For example:

• I left the house with my friend, Simon, and Terry.

If you read the example above (with an Oxford Comma), it is unclear whether I left the house with two people or three people. This could mean either of the following:

Two People my friend Simon Terry

Three People my unnamed friend Simon Terry

This ambiguity can be fixed by removing the Oxford Comma. For example:

• I left the house with my friend, Simon and Terry.
(Without the Oxford Comma, there is no ambiguity. It must be three people.)

The Oxford Comma can also eliminate ambiguity. For example:

• I left the house with the twins, Sarah and Jack.

With this sentence (without an Oxford Comma), it is unclear whether I left the house with two people or four people. This could mean either of the following:

Two People twins named Sarah and Jack

Four People unnamed twins Sarah Jack

• I left the house with the twins, Simon, and Terry.
(With an Oxford Comma), there is no ambiguity. It must be four people.)

Grammarians have been arguing over the pros and cons of the Oxford Comma for years, and that squabble is unlikely to end soon. One point is difficult to argue against: A comma before a conjunction makes the list clearer, especially when the list items themselves contain conjunctions. For example:

• On the London Underground, the Bakerloo Line goes through Harrow and Wealdston, Paddington, Oxford Circus, and Elephant and Castle.
(This list with an Oxford Comma is clearer than the list below.)
• On the London Underground, the Bakerloo Line goes through Harrow and Wealdston, Paddington, Oxford Circus and Elephant and Castle.
(With the Oxford Comma omitted (i.e., the second example above), those unfamiliar with London might think that "Oxford Circus and Elephant" was one station.)

Also, look at this:

• The Bakerloo Line runs between Harrow and Wealdstone, and Elephant and Castle.
(This is clearer.)
• The Bakerloo Line runs between Harrow and Wealdstone and Elephant and Castle.

Be Consistent – but Break Convention for Clarity

Follow one of the conventions, and stick to it throughout your document. 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.

Read more about the Oxford Comma.