When to Use a Comma Before “While”?

There are several principles to keep in mind when using a comma before while.

When while is used in a sentence, it is usually utilized as a conjunction. As such, it can have two different meanings. The first relates to time. In this instance, while describes an event taking place at the same time as another event. The second meaning indicates a juxtaposition or contrast. In these instances, while can be substituted with “although” and “whereas.”

How to use while in a sentence when referring to time

You do not use a comma before while when it was used in the temporal sense.

Examples:

Correct: The cat sat on the mat while the dog chewed on his toy.
Incorrect: The cat sat on the mat, while the dog chewed on his toy.

Correct: The train pulled into the station while we were buying tickets.
Incorrect: The train pulled into the station, while we were buying tickets.

How to use while in a sentence when referring to contrasting information

You do use a comma before while when it is used to create a contrast.

Examples:

Correct: I prefer soccer, while my brother prefers basketball.
Incorrect: I prefer soccer while my brother prefers basketball.

Correct: The price of everything has increased, while my wages haven’t changed.
Incorrect: The price of everything has increased while my wages haven’t changed.

Starting a sentence with while

When you use while as the first word of a sentence, you do not need to put a comma before it; grammatical rules state that a comma should be placed at the end of the clause introduced by while.

Examples:

Correct: While my sister enjoys horses, I prefer cows.
Incorrect: While my sister enjoys horses, I prefer cows.

Should I use a comma after whereas?

You do not usually include a comma after whereas. The general rule of thumb is: contrasting information requires a comma. When using whereas in a sentence, you should use a comma before it.

Examples:

Correct: I like soccer, whereas my friend prefers basketball.
Incorrect: I like soccer whereas my friend prefers basketball.