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Comma before "Which" and "Who"
The Quick Answer
When do you use a comma before "which"?An Extremely Simple Check
If you can replace your "which" with "that," don't use a comma before your "which."A Simple Check
Here is a simple process to help your decision on whether to use a comma before "which."- First: Look at the clause starting with "which."
- Check 1: If you'd be happy to put parentheses (brackets) around it or even delete it, then offset it with commas.
- Check 2: If you can't put it in brackets or delete it, then don't use commas.
A Bit More on Using a Comma before "Which"
Here's a slightly longer explanation.If the information provided by the clause introduced by "who" or "which" is necessary to define the person or thing it is describing (i.e., it's not just some extra information you could easily remove), then the clause is not offset with commas.
- The car which hit the snowdrift is a write-off.
- The car that hit the snowdrift is a write-off.


When to Use Commas before "Which" and "Who"
There is often confusion about when to use commas with "which" and "who." Unfortunately, there is no simple rule. Sometimes, there should be commas, and sometimes there should not. Here is the rule:Examples of "Which" and "Who" Clauses without Commas
Here are some examples of "who" clauses:- The boy who broke our window brought some flowers to the door.
- The driver who stole indicator bulbs for his own car was given a formal warning.
- Jeremy Buxton of 16 High Street who was born in Boston is the second person from the village to represent the country at basketball.
- Sarah has always been close to her parents who live in the same village as us.

- her parents who live in the same village
- her parents who live somewhere else
Real-life Examples
Here are some real-life examples of clauses that are required to define. (These are called restrictive clauses or defining clauses.)- The man who doesn't read good books has no advantage over the man who can't read them.
(Author Mark Twain)
- It is only shallow people who do not judge by appearances.
(Playwright Oscar Wilde)
- The man who can dominate a London dinner-table can dominate the world.
(Playwright Oscar Wilde)
- One should never trust a woman who tells one her real age. A woman who would tell one that would tell one anything.
(Playwright Oscar Wilde)
Examples of "Which" and "Who" Clauses with Commas
Remember that if the information provided by the "who" and "which" clause is just additional information (i.e., it is not required to define the word it is modifying), then it must be separated from the rest of the sentence with commas.In other words, if you'd happily put brackets around it or delete it, then you must at least put commas around it.
Examples:
- His youngest daughter, who was born on 16 June 1972, was selected for astronaut training.
- James Baker's cat made its own way home after it was accidentally left on the beach at Scarborough. James, who has lived in our village for 10 years, has just won the lottery.
- William Scott is a millionaire. William who bought his first house in the '80s is estimated to be worth more than 10 million pounds.
"Which" and "That"
You will notice that all of the examples in the section above use "who" and not "which." We have used "who" because using "which" without a comma is an unpopular practice (especially in the US). Here is an example of "which" without a comma:- Experience is a comb which nature gives us when we are bald.
"That" with a Restrictive Clause
When a clause is necessary for defining (or identification), it is called a restrictive clause. It is described as "restrictive" because it restricts the meaning of the word it modifies. It is also called a "defining clause," which, I think, is a more accurate term. There are never commas around a restrictive clause. When introducing a restrictive clause, the words "who" and "which" can be replaced with "that." (NB: There are never commas around a clause which starts with "that.")Here is an example with "who":
- The boy who broke our window bought me some flowers.
- The boy that broke our window bought me some flowers.
- The PC which keeps breaking down is under guarantee.
- The PC that keeps breaking down is under guarantee.
- The reprimand which you received was justified.
- The reprimand that you received was justified.
- The reprimand you received was justified.
Commas Are Being Used as Parenthetical Punctuation
If a clause just adds additional information, then it should be separated from the rest of the sentence with commas. You could equally use brackets or dashes. These are all types of parenthetical punctuation.- Manx cats, which live on the Isle of Man, have a longer life expectancy than normal domestic cats.
- Manx cats (which live on the Isle of Man) have a longer life expectancy than normal domestic cats.
- Manx cats – which live on the Isle of Man – have a longer life expectancy than normal domestic cats.
- Manx cats have a longer life expectancy than normal domestic cats.
Beware of Ambiguity
Look at the sentences below. Both are grammatically correct, but they have different meanings.- Manx cats, which live on the Isle of Man, have a longer life expectancy than normal domestic cats.
- Manx cats which live on the Isle of Man have a longer life expectancy than normal domestic cats.
Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.- Do you disagree with something on this page?
- Did you spot a typo?