Which / What year were you born? (2025)

Hello Members
I would like to know if "which" or "what" is acceptable in the following situations.
A.Which year were you born?
B. What year were you born?

I would ask "what year were you born?", but both versions are acceptable.

You can use "which" because there are a limited number of possible years, and you can use "what" because the number of years to choose from is immense (even though only a handful are plausible).

Hello Jektor,
Thank you very much for answer and the explanation.

Hello Jack,
Thank you very much for your explanation and the answer.

Neither version is acceptable. Nobody is born a year. Everybody is born in a year.
For me, the question therefore also needs to contain the word "in", either at the beginning (In which year were you born?) or at the end (What year were you born in?). It doesn't matter much whether you use which or what.

“What year were you born?” is what I would say. I wouldn’t use “which” or “in.”

Hello Edinburgher,
Thank you very much for your detailed explanation and answer. I see your logic.

Hello elroy,
Thank you very much for your answer. Reading all of the answers I think some kind of regional difference affects the way we ask this question. I would also like to know if using "in" is wrong or not colloquial.

Of course, what I would really ask is "When were you born?".

I would start the sentence with "what year" and end it with "in."

Where do you see the problem?

'What year were you born in?' is correct. Here's an example from a British source: What year was he [Andy Goldsworthy] born in?

A great many people say it the other way. Saying that something else is technically more correct doesn't change the fact that the other way is idiomatic.