Comma rules

Most comma decisions fall under eight rules. Step through them below, then use the checklist when you edit.

See it work

Step through the eight comma rules:

We need flour, eggs, and milk.

✓ Separate three or more items in a list. (The comma before "and" is the Oxford comma; optional in some styles.)

Commas you should not add

Do not put a comma between a subject and its verb (The people who arrived late, missed the talk ✗), before "that" clauses, or between two verbs sharing one subject (She wrote the report, and sent it ✗ unless you want the pause).

The comma splice

A comma alone cannot join two complete sentences. That error is called a comma splice; see the comma splice guide for four fixes.

Frequently asked

Does a comma go before "because"?

Usually not. Add one only if the sentence would be misread without it.

Comma before "but"?

Yes when "but" joins two complete sentences: "I called, but nobody answered." No when it does not: "I called but got no answer."

Comma after "however"?

Yes when it starts a sentence or follows a semicolon as a transition: "However, we disagreed."