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Modals of Possibility: May, Might, Could

May 28, 2015

We just 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.)

Some people have argued for slight differences in meaning, and this 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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Comments (29)

Tanya Trusler(Author)

Hi guys,

A few people have been discussing 'may' on Twitter (https://twitter.com/ESLlibrary). 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. :)

Reply to Comment

Susan W.(Teacher)

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(Author)

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

isabella (Guest)

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 :)

Reply to Comment

Hong (Guest)

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(Author)

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.'

Tanya Trusler(Author)

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,

Irma S.(Teacher)

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

Reply to Comment

Tanya Trusler(Author)

I'm happy to hear that. Thanks!

Samhitha (Guest)


Reply to Comment

Tanya Trusler(Author)

You're welcome!

Kim (Guest)

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.

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    Tanya Trusler(Author)

    Thanks for the lovely comment, Kim! I'm glad you found this post helpful. Here's an index that has most of the grammar posts on our site so you can easily find what you're looking for:


    Devendra Nath Tiwari(Guest)

    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

    Reply to Comment

    Tanya Trusler(Author)

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

    Narasinga Rao B(Guest)

    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. .

    Reply to Comment

    Tanya Trusler(Author)

    Hi Narasinga,

    Good question. The main difference is that 'would' implies a hypothetical situation (see this post on conditional sentences: https://blog.esllibrary.com/2013/03/14/an-easy-way-to-teach-conditionals/). 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.

    Mohamed A.(Member)

    Thank you very much for this helpful lesson on “would” , I would like to do me a favor , if you could possibly provide more highlight on different uses of ‘ would ‘ not the conditionals

    Reply to Comment

    Tanya Trusler(Author)

    Hi Mohamed,

    This is a great idea for a future blog post! I'll work on that soon. For now, I can tell you that "would" is common in these situations:
    1. conditional sentences (If I had more money, I would buy a house.)
    2. making offers (e.g., Would you like some more coffee?)
    3. asking about preferences (e.g., What would you like to drink? / Which one would you rather have?)
    4. talking about past situations (e.g., When I was young, I would go to the park every day.)

    Danilo V.(Member)

    Hello everyone, i´m interested in the negative form of might and could, how do we use them? and what do they mean in the negative?
    please answer me as soon as possible. Thank you.

    Reply to Comment

    Tanya Trusler(Author)

    Hi Danillo,

    That's a great question! Both might and may can be negative modals of possibility in the present or future.

    • I might not go to the party tonight.
    • She may not travel next year because of the pandemic.
    • I know you think that berry is edible, but it might not be! It may be poisonous.

    Be careful with could. The negative form of could is only used for past ability, not present/future possibility!

    • I couldn't go to the meeting yesterday because I was sick. (= I was not able to go.)

    Hope that helps!

    Helen Connolly(Guest)

    Hi, my student asked me what the difference was between "might" and "could". For example, "I might after a coffee after this lesson" is correct. But if I use "could" in this sentence, it seems to have another meaning, but I'm uncertain of the difference. Hope you can help me out. Thanks.

    Reply to Comment

    Tanya Trusler(Author)

    Your student asked a great question! You can use any modal of possibility in that sentence with the meaning of "maybe" (i.e., I might/could/may have a coffee after this lesson). But your student was probably thinking that "could" could have another meaning here, that of past ability, which would also be correct. Usually context helps clear up which modal is being used.

    • I could have a coffee after this lesson today if the class doesn't run late. (= modal of possibility, future meaning)
    • I could have a coffee after class yesterday because I had an hour until my next class. (= modal of ability, past meaning)

    Giri K.(Member)

    Hello Mam, this is Girikumar from the south India. Hope u r doing well. Thank u so much for this blog concerned with English grammar. For, it really helped me get my doubts about modal verbs clarified. But still, something kind of makes me feel like it is not 100% in terms of subtle distinctions between "may, "might", & "could" because to me they are tricky. Let me get this straight. When it comes to the modals "might", "may", & "could", they can be used to talk about future possibilities.

    So, what is the subtle distinction between, "You might like any of these songs that we will paly for you on the show." & "You could like any of these songs that we will play for you on the show." & "You may like any of these songs that we will play for you on the show."
    I believe that they must have some distinction between them or else they wouldn't be in use.

    My next question is, can we use could in negative to talk about future possibility? I know that other modalities like "may" & "might" can be used. Yet, this doubt has been on my mind so long.
    For example: He might/may not come tomorrow. (This is correct as to what many other grammar books say.)
    What if we say,
    He couldn't come tomorrow.(Is it not correct? If so, I request that you expalin why.)

    I will be looking forward to your reply. Hope u reply and make me happy. By the way, stay safe, mam.

    Reply to Comment

    Tanya Trusler(Author)

    Hi Giri,

    Great questions. Some people do think there is a slight difference in meaning. My opinion is that it varies and is not worth mentioning to students, but you're correct that there could be a slight difference. For example, Cambridge Dictionary offers an explanation about a possible difference in meaning here: https://dictionary.cambridge.org/grammar/british-grammar/could-may-and-might
    But note that even with that explanation, they say "Many native speakers disagree on which one expresses more or less certainty."

    To me, the only really important differences are that "may" is more formal than "might" or "could" in American and Canadian English, and that these modals can all be used in ways besides possibility (for ability, necessity, requests, offers, etc.).

    As for negative sentences, it's best to avoid "could not" since it is almost always used to show past ability, not present or future possibility. For example:
    • Lisa could not go to the party.
    (Past ability = She didn't go to the party.)
    • Lisa might not go to the party. (Future possibility = She's not sure if she will go to the party or not.)

    For possibility, it's much better to use "might not" or "may not" (or "can't" if you're certain).

    I hope you stay safe too, Giri!

    Giri Kumar(Guest)

    Thank u so much for ur answers to my previous questions, mam.
    Could u differentiate between "relatively speaking" & "comparatively speaking" & "technically speaking"?
    They still get on my nerves as to why I hesitate to use them while speaking in English.
    It would be way helpful for me if you could explain the differences between them in exhaustive terms.
    Thank u, mam.

    Reply to Comment

    Tanya Trusler(Author)

    You're welcome, Giri! To answer your next question, "relatively speaking" is far more common than the other two, so that's what I would normally use and expect to hear. Merriam-Webster has a definition for relatively speaking, but not for the others: https://www.merriam-webster.com/dictionary/relatively%20speaking

    To compare something to one or more other things, you can use "relatively speaking" or "comparatively speaking," with the first one being more common. "Relatively speaking" also has another meaning (#2 in the MW entry) where you can use it to express an opinion that might not be true for everyone. For example, "My presentation went well, relatively speaking" means that it went well for me, but it's possible that others didn't think so (MW entry #2). It can also mean it went well in comparison to my past presentations or to the presentations of my classmates (MW entry #1).

    "Technically speaking" isn't that common, but you can use it to mean "with regard to a strict interpretation" (https://www.merriam-webster.com/dictionary/technically, entry #1). For example, "An avocado is a fruit, technically speaking" since the scientific classification is a fruit, but many people think of it as a vegetable (i.e., it's used in cooking more like a vegetable than a fruit). Hope that helps!

    Giri Kumar(Guest)

    Thank u so much for ur reply with answer to my recent question, mam.
    A lot more are still unanswered to me. One of them is the subtle difference between, "In order to" & "so as to".
    Could u tell me if they do have subtle difference between them in terms of usage, mam?

    Reply to Comment

    Tanya Trusler(Author)

    Hi again Giri, the difference between these has more to do with sentence position than meaning. Off the top of my head, these two meanings are identical. They're both used formally or informally too (the most informal case is with "to" alone). One difference is that "in order to" can begin a sentence, whereas "so as to" cannot. Another difference is that "so as to" isn't all that common. I myself use "to" or "in order to," but I've never used "so as to." Hope that helps!
    Examples (with the same meaning):
    - They had to reschedule the meeting in order to accommodate the different time zones.
    - In order to accommodate the different time zones, they had to reschedule the meeting.
    - They had to reschedule the meeting to accommodate the different time zones.
    - To accommodate the different time zones, they had to reschedule the meeting.
    - They had to reschedule the meeting so as to accommodate the different time zones.

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