What's the difference between the following:

  1. If he is in the US now, he would be in New York.
  2. If he is in the US now, he will be in New York.

Does #2 necessarily mean that he will be in New York at a future date if the condition holds?

Can #2 mean that he must be in New York now if the condition holds?

"Will" can mean "must", can't it, as in "That will be John knocking at the door"?

2 Answers 2


Context is the key.

  1. For example, if you know that he is on his way to the US:

    If he is in the US (by) now, he will be in New York.

  2. If you know that he's in the US, and are making a guess about the city:

    If he is in the US now, he would be in New York.

  3. If you don't know where he is and are making both the assumptions:

    If he were in the US, he would be in New York.

  • The OP uses the same tense "If he is" in both sentences.
    – Mari-Lou A
    May 17, 2015 at 18:36
  • Possible, depending upon the context and what is really intended. "would" can also be used, among others, in a situation of uncertainty. Therefore, "he would be in New York" = he will probably be in New York.
    – Sankarane
    May 17, 2015 at 18:45
  • I'm just pointing out that in your answer you changed the tense, you wrote "If he were", the change in meaning is subtle.
    – Mari-Lou A
    May 17, 2015 at 18:50
  • Oh, that's the tense and form (one form, invariable for all pronouns, such as I, you, we, he, etc.) used while making an assumption.
    – Sankarane
    May 17, 2015 at 18:57
  • So are you saying the OP has made a grammatical error? If that is the case, please edit your answer and address this point. Otherwise your second phrase is skirting the issue.
    – Mari-Lou A
    May 17, 2015 at 18:58

As John Lawler has taught us countless times (quoting from this answer):

Modal auxiliary verbs ("modals") are very irregular and have extremely complex grammar. Every modal has two kinds of meaning: its Epistemic sense and its Deontic sense.

Epistemic meanings are abstract and refer to logical predictions and conclusions: This might/must/could/should/may/will/would be the place.

Deontic meanings are social and have to do with obligations, permissions, and prohibitions: She may/can/should/must go to the ball.

will and must both are modals and both can have epistemic as well as deontic meanings. So yes, will can mean must, but must doesn't always imply certainty (as in, "This must be where it took place", he speculated.)

According to me, your first example is epistemic. The speaker is predicting he's in New York, certainty isn't guaranteed.

The if...will construction is that of the conditional mood, not the subjunctive mood as you've tagged it. It doesn't define limits of certainty.


  • IF I give you 12 apples, you WILL have a dozen apples. (absolutely)
  • IF you eat 12 apples, you WILL fall ill. (maybe, maybe not)

Bottom line, you should never rely on modal for certainty. Introduce other suitable words in the sentence.

If he is in the US now, he will possibly/probably/definitely be in New York.

EDIT: You can't use will to speculate about the future, and you can't use would to speculate about now. If you use will, you'd be speculating about the present. See sense 6 in Oxford. If you use would, you'd be speculating about the future.

  • Would #2 not be the case for someone stating it with certainty? I seem to recall a lot of similar sentences e.g. in movies where the protagonist knows where the person they're looking for will be found. Knowing with certainty might be an overstatement on their part, but not specifically grammatically incorrect, no?
    – Flater
    May 8, 2015 at 7:52
  • @Flater So, for you, the would-version, i.e. 1, is less definite than 2?
    – Apollyon
    May 8, 2015 at 8:00
  • It seems to me "would" is more a statement of historical evidence, or assumption about where he'd want to go. It's been the case often, so it's fair to presume the same thing happening now. Whereas "will" is more focused on it being correct now (for whatever reason). This is just interpretation though. Not application of known grammatical rules.
    – Flater
    May 8, 2015 at 8:05
  • @Flater: You're right. Edited the post.
    – Tushar Raj
    May 8, 2015 at 8:32
  • @Flater You just produced a sentence of the sort that interests me: "If you use will, you'd be speculating about the present." What does 'would' mean here?
    – Apollyon
    May 8, 2015 at 12:09

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