In one of my posts ("Farthest" vs. "The farthest") I said

Is there some difference in meaning? When would I use which?

I guess it is grammatical, though it does not seem to be idiomatic, according to Google Ngram

enter image description here

"Ngrams not found: When would I use which, When should I use each" indicate somehow people rarely say it that way.

However, if I had said this way

Is there some difference in meaning? When to use which?

The second sentence dose not seem grammatical.

What am I missing? Could someone please give a hint? Thanks in advance.

  • You are missing context. How can be tell you without a sentence at least? Please provide one. And please use a better title such as farthest or the farthest.
    – Lambie
    Commented Sep 2, 2020 at 16:07

1 Answer 1


I would definitely avoid using "When to use which?" This doesn't really make sense as it is missing the auxiliary verb. "When would I use which?" is good and understandable but still sounds a tiny bit strange. Best is "When should I use each one?". Using "would" instead of "should" is perfectly fine but "should" is more common for this. enter image description here

  • Thank you. I updated my OP. Google Ngram says "not found" for "When should I use each".
    – WXJ96163
    Commented Apr 1, 2020 at 8:48
  • It might be that it's a personal preference or dialectal thing. To me "When should I use each one" sounds the best. If you or others disagree, you could try rewriting to the sentence. Maybe something like "How do I know which one to use?" Commented Apr 1, 2020 at 10:22
  • 1
    What I meant is not a disagreement, and it is not an agreement either. I'd just like to know how to choose expressions. I didn't realize it is a matter of preference, that's why I made the first comment. I got it now. Thank you, that's very kind of you. – WXJ96163 14 mins ago Delete
    – WXJ96163
    Commented Apr 1, 2020 at 23:29
  • 1
    "would" conveys a different flavor than "should" to me. "When should I" sounds like a genuine question which is mostly unbiased. "When would I" sounds like a question about a situation that the questioner finds unlikely, strange, or surprising. Something like "Hey, whenever you jump over a cow, watch out for their horns!" - "(When/Why) would I jump over a cow?". Whereas the question "Why should I jump over a cow" sounds like asking for physiotherapeutical benefits of cow jumping, and "When should I..." sounds like asking what the best time for one's daily cow jumping routine is.
    – dialer
    Commented May 4, 2022 at 6:24

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .