Extra help for commas

Do not use commas

  • In a list of three or more items, do not use the comma (called serial comma or Oxford comma) before the word “and” or “or,” unless needed for clarity: red, white and blue
  • When the subject of the two clauses is the same and is not repeated in the second: She is working on new research and hopes to publish soon.
  • Before “because” (unless you need the comma to prevent confusion because your sentence could have two meanings)
    • The Okies had to leave their farms because the drought conditions had ruined their farms.
    • I knew that President Nixon would resign that morning, because my sister-in-law worked in the White House. (Without that comma, the sentence says that Nixon’s resignation was the fault of my sister-in-law.)
  • Before “such as” or “including” when a sentence wouldn’t make sense without the words that follow: I love moments such as those.
  • At the start of an indirect or partial quotation: She said the vaccine will be ready in the next year or two.
  • In names of people with Jr. and Sr.: John Smith Jr.

Do use commas

  • Before the word “and” or “or” in a list of three or more items when there is a compound list of things and the last part includes the word “and”: The colors in the image were purple, orange, green, and white and gray mix.
  • In direct address: Sarah, please turn on the fume hood.
  • To separate a series of adjectives equal in rank: If the commas could be replaced by the word and without changing the sense, the adjectives are equal:
    a thoughtful, precise manner or a dark, dangerous street
  • To separate duplicated words that otherwise would be confusing: What the problem is, is not clear.
  • To set off someone’s age: Maude Findlay, 48, was present.
  • With “yes” and “no”: Yes, I will be there.
  • With full dates: When a phrase refers to a month, day and year, set off the year with a comma: November 5, 2016, is my thirtieth birthday.
  • With introductory clauses and phrases: When he had tired of the mad pace of New York, he moved to Dubuque.
    (No comma needed when phrase is fewer than four words: Outside you’ll find the equipment.)
  • Before coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so) that join two independent clauses that could stand apart as separate sentences: She was glad she had looked, for a man was approaching the house.
  • After names of states and nations used with city names: His journey will take him from College Station, Texas, to Fargo, North Dakota, and back.
  • For any number containing four of more digits: 4,000 or 10,000
  • To set off credentials: Jane Doe, PhD, is a new professor.