“What” and “which” are both used for asking questions. They can even be used interchangeably in many cases. However, they’re not always interchangeable. So check out our guide to using “what” and “which” in questions to make sure your writing is always error free.
“What” and “Which” in Questions
“What” and “which” are both interrogative pronouns. In other words, we can use “what” and “which” in questions when we want someone to specify something. For example:
What TV shows do you watch? ✓
Which TV shows do you watch? ✓
Here, we’re asking someone to specify the TV programs they enjoy. We can use either “what” or “which” in this case because there is a large but not unlimited number of potential answers.
Open Questions vs. A Limited Range of Answers
The difference between “what” and “which” emerges when we’re dealing with questions that are either very open or fairly limited. When a question is very broad, we use “what”:
What shall we do today? ✓
Which shall we do today? ✗
Here, “which” is not grammatically incorrect. But it does imply a limited range of choices (e.g., as if the conversation were about either going to the beach or going to the movies). “What,” on the other hand, leaves the question open to any number of possible answers.
But we can reverse this by asking a question with a limited range of choices:
What hand do you write with? ✗
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Which hand do you write with? ✓
In this case, “which” is correct because the answer has to be either “left” or “right.” We also use “which” before “of” and “one,” as these imply a limited set of possible answers:
Which of my hats do you like most?✓
Which one should I wear?✓
Here, using “which” suggests a limited number of hats from which to choose.
Summary: What or Which?
You can use both “what” and “which” in questions when asking for information that specifies something. Generally, when a question is open to many answers, it is better to use “what”:
What shall we do today?
But when there are a limited number of choices, use “which”:
Which hand do you write with?
If you’d like help getting “which” and “what” in order, just let us know.