Modals of Possibility: May, Might, Could

We might learn something!

There are many modals in English—modals of ability, possibility, necessity/obligation, and advice, to name the most common—and students can get confused by all the different functions and meanings. Some modals can be used for more than one purpose (such as could for past ability or present/future possibility), so it’s no wonder they sometimes struggle! Presenting modals by function can help English language learners keep them all straight. Today, let’s focus on modals of possibility.

May, Might & Could

In English, there are three main modals of possibility: may, might, and could.

1. Pattern

Modal + Base Verb

Remind lower-level students that a base verb is one with no endings(no -ing, -ed, -s, etc.). The modal always comes before the base verb.

  • We might go to the party tomorrow night.
  • She could decide to join us.

2. Function

We use these modals to describe a possible action. Because of the uncertainty, these modals are often used to talk about the future, though sometimes we want to express possibility in the present.

  • I may go traveling next year. (future possibility)
  • My keys might be in the car. (present possibility)

3. Examples

  • They might attend the awards ceremony tomorrow night.
  • He could call you back tonight.
  • We could choose a new color of paint for the bedroom.
  • I might join you if I finish early.
  • The results of the study may shed some light on this condition.

4. Differences in Meaning

When it comes to the meaning of may, might, and could for possibility, I would argue that, at least in North American English, there is no difference in meaning except formality. Whatever you do, please remind students that may is quite formal! Textbooks always present the three modals together, and students might use may in everyday speech unless we point out that it’s not common to do so. Emphasize that they might see and use may in formal writing, but in speaking and informal writing, they should stick to might and could. (Note that this is the preference in North America, but I believe that may is quite common in speaking and writing in British English.)

People have argued for slight differences in meaning (there’s a good blog post about it on the OxfordWords blog), and it might be an interesting discussion for higher-level students. But for most students, the difference is irrelevant and these words are interchangeable.

Remind students that could is also used for past ability. There is usually a reference to the past in the sentence or context, which helps learners recognize when could is referring to ability. Note the differences:

  • He could finish his project tonight. (possibility)
  • He could swim when he was a child. (past ability)

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Leave a Comment ↓

  1. Narasinga Rao B says:

    Jun 15, 2018 at 3:21 am

    to talk about the result or effect of a possible situation: this is about “would” usage to talk about future possibility. I noticed it on british English blog. They have given an example also like:
    It would be very expensive to stay in a hotel. My doubt is what happens if we use ” could be” in the place of “would be”. Is there any nexus between “could”and”would” to talk about future possibility. .please explain. .

    • Tanya Trusler says:

      Jun 18, 2018 at 2:03 pm

      Hi Narasinga,

      Good question. The main difference is that “would” implies a hypothetical situation (see this post on conditional sentences: So “It would be very expensive to stay in a hotel” means that you’re unlikely to do it. You might just be discussing your hopes and dreams. If you said “That hotel could be expensive” the meaning is that you are planning to look into the prices of that hotel. In this situation you are probably planning a trip and are deciding on which hotel you’d like to stay in (you’re discussing the possibilities). In summary, “could” is likely and possible whereas “would” is unlikely or impossible.

  2. Devendra Nath Tiwari says:

    Sep 07, 2017 at 10:49 pm

    Wow its so good that i have no words to appericiate u thank u for giving knowledge on this topic u have made this topic very easy

    • Tanya Trusler says:

      Sep 11, 2017 at 7:46 pm

      I’m glad this post helped you! Thanks for commenting.

  3. Kim says:

    May 23, 2017 at 7:40 pm

    I used to listen BBC 6 minutes grammar PodCast.
    To topic of today was a “May, might, could”
    Anyway, I confused the exact differentication of those, because they didn’t say about that.
    I solved the problem thank to your comment !! there is no differentiation, so that they didn’t give any comment about that.

    Anyway, thank you.

    And, I looked around your blog.
    There are many useful information here.

    I think I might visit here frequently.

  4. Samhitha says:

    May 22, 2017 at 2:39 am


  5. irmasanta says:

    Jun 13, 2015 at 9:21 pm

    thank you it is very useful, Now, I feel better about this topic.

    • Tanya Trusler says:

      Jun 16, 2015 at 5:12 pm

      I’m happy to hear that. Thanks!

  6. isabella says:

    May 29, 2015 at 9:00 pm

    mostly what i find is people saying “may you pass me the salt?” as opposed to “could you pass me the salt?” i almost only encounter that in situations where the person addressed is seen as a person in authority – so what you’re saying about formality makes sense. i guess it’s a confusion about when to use what modality of formality, which, of course, is confusing because english is a mess :)

    • Tanya Trusler says:

      May 29, 2015 at 11:22 pm

      Hi Isabella,

      Thanks for bringing up another confusing aspect about modals. “May you pass me the salt?” is incorrect because we can’t use “may” for offers and requests. For offers and requests, where you’re offering to do something for someone, or where someone is asking you to do something (like in your example sentence), we can only use “can” and “could.” Again, “could” is more formal than “can.”

      – Could you pass me the salt? (a bit more formal)
      – Can you pass me the salt? (casual)

      I agree that modals can be confusing, but don’t worry too much about formality. We are usually pretty casual in spoken English. I would only use the more formal modals when meeting someone for the first time or when addressing my boss (or when a young student addresses a teacher).

      Take care,

      • Hong says:

        Aug 01, 2017 at 9:23 pm

        I’m not sure about that part when you say “we can’t use “may” for offers and requests”. because I can use may for offering and request.
        e.g. May I help you?
        May I use your phone please?
        And they are both formal.

        • Tanya Trusler says:

          Aug 03, 2017 at 3:59 pm

          Hi Hong,

          Great question. I should’ve been clearer in that “may” isn’t used with offers and requests when the subject is “you.” So we can’t say “May you pass me the salt?” But you’re right that “may” can be used in offers when the subject is “I” as in “May I help you?” It’s quite formal, but it’s pretty common to hear on a business telephone call or in a store, for example.

          “May I use your phone, please?” is a good example of asking for permission. Using “may” with permission is pretty formal, but it is indeed correct. See my comment directly below (from May 29, 2015) for more examples regarding permission. I also think there’s a fine line between the meaning of permission and request, so don’t worry about the terminology. Just be aware that you’re correct in assuming we can use “may” in formal situations when the subject is “I.”

  7. Tanya Trusler says:

    May 29, 2015 at 8:23 pm

    Hi guys,

    A few people have been discussing “may” on Twitter ( Since space is so limited on Twitter, I’ll address the questions here.

    Isabella asked why ESL speakers think “may” is more polite than “could.” Brian responded that they may have been told it’s correct or more formal rather than being polite, and Isabella asked who would have told them that.

    I think the confusion is that there is more than one use for “may.” For modals of possibility, students in North America are usually told by their teachers that “may” is more formal. For instance, I tell my students that I would never say “I may go to the party tonight” in casual speech, because it sounds very formal to me. I would say “might” or “could” in that sentence. But I wouldn’t be surprised to hear something on the news (a more formal setting) with “may,” such as “The suspect may be released on bail on Friday.”

    Remember that it depends on your region. I’m from Vancouver, Canada, but I think I speak for all of North America (correct me if I’m wrong). However, in Britain, I’ve been told that “may” is much more common and can be used in casual speaking (again, correct me if I’m wrong).

    Now, as for “may” being polite, we need to look at modals for requests and permission. When we ask someone for something, or grant someone permission, we use the modals “may,” “could,” or “can.”
    – May I use the photocopier? / You may use the photocopier. (very polite)
    – Could I use the photocopier? / You could use the photocopier. (polite)
    – Can I use the photocopier? / You can use the photocopier (casual)

    Again, this could depend on the region, but I think the degree of politeness for this type of modal is world-wide.

    Hope this helped! I see a blog post on modals of permission and requests in my future. Keep your questions coming. :)

    • Susan Wessling says:

      Mar 31, 2016 at 7:41 pm

      When I was in school if we asked, “Can I go to the ladies room?” The teacher would reply, “Yes you can but you may not.” She was trying to teach us the difference between can (have the ability to do something) and may (asking if you could do something). I live in Central Mass and grew up in a suburb in which you literally could walk into Boston. Here, it is definitely considered more polite to ask “May I … ” than “Can I …” (I have told many of my students that teacher’s response and they have laughed at it, but remember it and I have had one even jokingly say it to me.) I think in those cases (Can I or May I ) there is a difference, at least as I have been taught it and how I still see others teach it as well.

      • Tanya Trusler says:

        Mar 31, 2016 at 7:54 pm

        That’s a great anecdote to illustrate the difference between modals of ability and permission. Thanks for sharing, Susan!

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