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English grammar

May, Might, Could for Possibility

Updated 27 Oct 2026 4 min read LingoLadder Editorial Team
Cover: may, might, could for possibility — a cloudy sky with an umbrella and a question mark showing perhaps
Short answer

Use may, might or could plus the base verb to say something is possible: 'It may rain', 'She might be late', 'We could win'. All three mean roughly 'perhaps', and all are followed by the base verb with no 'to'.

On this page10 sections · tap to jump
  1. 01The rule
  2. 02May, might, could — forms and likelihood
  3. 03Example sentences
  4. 04Common mistakes
  5. 05A short conversation
  6. 06Usage notes
  7. 07Compared with…
  8. 08Practice
  9. 09Quiz
  10. 10Recap cheat-sheet

Level: B1. When you are not sure something is true or will happen, English gives you three handy modal verbs: may, might and could. Each means roughly perhaps. This lesson shows how close they are, where they differ, and how to make them negative without changing the meaning by accident.

The rule

A modal verb is a helping verb that goes before the base form of the main verb and keeps the same shape for every subject: I may go, she may go (never mays). After may, might and could you use the base verb with no to: may rain, not may to rain.

All three express possibility — you think something is perhaps true now, or perhaps will happen in the future: It may be true, She might call tonight, We could be wrong. They do not say the event is certain; they say it is one real chance among others.

The differences are small. May and might are the closest pair, and you can usually swap them; might often feels slightly less certain or more tentative. Could adds the flavour of one possibility among several: The keys could be in the car, or in the kitchen. In everyday speech the three overlap so much that a learner is safe using any of them for a simple “perhaps”.

The negatives are where care pays off. The negative of possibility is may not or might not: She may not come means perhaps she will not come. Do not use couldn’t here — couldn’t means impossible (That couldn’t be true), not simply unlikely.

May, might, could — forms and likelihood

Form Use Example
may + base verb possibility (often neutral) It may rain later.
might + base verb possibility (often less certain) She might be at home.
could + base verb one possibility among several The answer could be wrong.
may not / might not + base negative possibility (perhaps not) He may not agree.

Think of a rough likelihood scale: will (certain) → may / might / could (possible, about 50/50) → won’t (certain not). The three possibility modals all live in the uncertain middle; they do not tell you which side of 50% you are on.

Example sentences

  1. It may rain this afternoon.
    Present/future possibility with may.
  2. She might be at work right now.
    Possibility about the present with might.
  3. We could go to the beach tomorrow.
    One option among several with could.
  4. He may know the answer.
    Perhaps he knows it.
  5. They might not come to the party.
    Negative possibility — perhaps they won't.
  6. The train could be late again.
    A real chance, one of several outcomes.
  7. I may travel to Spain next year.
    A future plan that is not certain.
  8. You might like this film.
    A tentative suggestion.
  9. This could be the best option for us.
    Possibility weighed against others.
  10. She may not have my number.
    Perhaps she doesn't have it.
  11. It might snow tonight.
    Uncertain future weather.
  12. We could be wrong about the date.
    Admitting a possible mistake.
  13. He may call later this evening.
    A possible future action.
  14. The keys might be in your coat.
    A guess about where they are.
  15. Prices could rise next month.
    A possible future change.
  16. I might not finish in time.
    Perhaps I won't finish.
  17. They may arrive before us.
    A possible outcome.
  18. That could explain the noise.
    A possible explanation.
  19. We may need more chairs.
    A possible need.
  20. She might prefer tea to coffee.
    A tentative guess about a preference.

Common mistakes

  • ❌ It may to rain. → ✅ It may rain. No to after may, might or could.
  • ❌ She mights come. → ✅ She might come. Modals never add -s for he/she/it.
  • ❌ He couldn’t be at home (= perhaps he isn’t). → ✅ He might not be at home. For “perhaps not” use may not / might not; couldn’t means impossible.
  • ❌ They don’t may come. → ✅ They may not come. Make the negative with not after the modal, not with don’t.
  • ❌ Can I be wrong about this. → ✅ I could be wrong about this. For a tentative “perhaps” about a fact, use could/might, not can.
  • ❌ It might will rain. → ✅ It might rain. Do not put two modals together; the modal already covers the future.

A short conversation

A: Do you know where Sam is? B: I’m not sure. He might be stuck in traffic, or he may have forgotten. A: Could he be at the other entrance? B: Maybe. He might not have seen my message, so I’ll call him.

Usage notes

  • Permission vs possibility. May has a second, more formal meaning: asking for or giving permission — May I come in?, You may leave now. That is not possibility; the possibility meaning is “perhaps”. Context makes it clear, and the polite-request lesson covers permission in detail.
  • Present or future. These modals cover both a guess about now (She might be asleep) and a possible future (It might rain tomorrow). English does not change the modal; the time comes from the rest of the sentence.
  • No stacking modals. You cannot say will might or might can. Use one modal; it already carries the future or the ability idea.
  • Softening. Could and might are also polite ways to soften a suggestion: You could try the other shop, You might want to check the date.

Compared with…

  • Must and can’t for deduction are the strong end of the same scale. When you are almost sure, you use must (positive) or can’t (negative): He must be exhausted / That can’t be right. May/might/could stay in the uncertain middle. See Must, Can’t, Might for Deduction.
  • Must and mustn’t express obligation and prohibition, a completely different job from guessing how likely something is. Keep the two meanings of must apart. See Must and Mustn’t (Strong Obligation).

Recap card for may, might and could showing possibility, the negative may not and the likelihood scale

Quick recap before you practise.

Practice

Practice

May, might, could practice

Try each one, then press Check. No sign-up, nothing is sent anywhere — it all runs in your browser.

1 Choose the best option: 'Take an umbrella — it ___ rain later.'
Show answer

might — Might + base verb expresses possibility; no 'to' after the modal.

2 Which means 'perhaps she will not come'?
Show answer

She might not come. — Might not = perhaps not. Couldn't/can't mean impossible; mustn't means forbidden.

Hint: base verb after could

Show answer

be — After could you use the base verb: be.

Hint: modal + not

Show answer

may not — Add not after the modal: may not / might not agree.

5 Put the words in order to make a possibility sentence.

Show answer

She might be at home — might + base verb (be) expresses possibility.

6 Match each modal to its best description.

  • may
  • might
  • could
  • might not
Show answer
  • may → possible (neutral)
  • might → possible (less certain)
  • could → one option among several
  • might not → perhaps not

All three sit in the uncertain middle; the negative of possibility is may/might not.

Quiz

Check yourself

May, might, could quiz

12 questions · pick an answer and you'll see straight away if it's right.

0/12 0 answered
  1. 1Choose: 'Those clouds are dark — it ___ rain.'
    Show answer

    might — Might + base verb shows possibility; no 'to' and no doubled modal.

  2. 2Which sentence means 'perhaps he is not at home'?
    Show answer

    He might not be at home. — Might not = perhaps not. Couldn't/can't = impossible; mustn't = forbidden.

  3. 3Which sentence is correct?
    Show answer

    She might win. — Modals take the base verb with no -s and no 'to'.

  4. 4Choose: 'I'm not certain, but the answer ___ be 42.'
    Show answer

    could — Could expresses an uncertain possibility — one option among several.

  5. 5What does 'It might snow tonight' mean?
    Show answer

    Perhaps it will snow. — Might expresses possibility: perhaps it will snow.

  6. 6Choose the correct negative possibility: 'They ___ come to the party.'
    Show answer

    may not — Form the negative with not after the modal: may not. Couldn't = impossible.

  7. 7Which sentence is WRONG?
    Show answer

    She might will call. — You cannot stack two modals; 'might will' is wrong. Use 'might call'.

  8. 8Choose: 'The shop is closed, so I ___ have to come back tomorrow.'
    Show answer

    might — Might + base verb (have) shows a possible future need.

  9. 9Which modal adds the sense of 'one option among several'?
    Show answer

    could — Could often points to one possibility among several.

  10. 10Choose: 'She ___ prefer tea; I'm not sure.'
    Show answer

    might — Might expresses a tentative guess; no 'to' after the modal.

  11. Show answer

    may not — May not / might not express 'perhaps not' — uncertainty, not impossibility.

  12. 12Which is NOT a possibility meaning?
    Show answer

    May I leave early? — 'May I leave early?' asks for permission — a different meaning of may.

Recap cheat-sheet

Idea Use Example
it is possible may / might / could + base It may / might / could rain.
perhaps not may not / might not + base She might not come.
impossible (not this) can’t / couldn’t That can’t be right.
almost certain (not this) must He must be tired.

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Grammar path

125 topics 125 ready now
A1 30 topics · 30 ready
  1. 01 Verb 'To Be' in the Present (am, is, are)
  2. 02 Subject Pronouns: I, You, He, She, It, We, They
  3. 03 Present Simple: Affirmative and the -s Ending
  4. 04 Present Simple: Negatives and Questions (do/does)
  5. 05 Articles: a / an and When to Use Each
  6. 06 The Definite Article 'The': When to Use It
  7. 07 Zero Article: When to Use No Article
  8. 08 Plural Nouns: Regular and Irregular Forms
  9. 09 This, That, These, Those (Demonstratives)
  10. 10 Possessive Adjectives: my, your, his, her
  11. 11 Possessive 's and s' (Showing Belonging)
  12. 12 There Is / There Are (Saying What Exists)
  13. 13 Have Got: Talking About Possession
  14. 14 Can and Can't for Ability
  15. 15 Present Continuous (am/is/are + -ing)
  16. 16 Imperatives: Giving Orders and Instructions
  17. 17 Adjectives: Position and Basic Use
  18. 18 Prepositions of Place: in, on, at
  19. 19 Prepositions of Time: in, on, at
  20. 20 Question Words: What, Where, When, Who, Why, How
  21. 21 How Much vs How Many
  22. 22 Countable and Uncountable Nouns
  23. 23 Some and Any: Which One to Use
  24. 24 Object Pronouns: me, you, him, her, us, them
  25. 25 Adverbs of Frequency and Their Position
  26. 26 Like, Love, Hate + -ing (Expressing Preferences)
  27. 27 Would Like: Polite Wants and Offers
  28. 28 Making Requests: Can, Could, May I
  29. 29 Past Simple of 'To Be' (was / were)
  30. 30 Let's and Shall We: Making Suggestions
A2 25 topics · 25 ready
  1. 31 Past Simple: Regular Verbs and -ed Spelling
  2. 32 Past Simple: Irregular Verbs (go, see, have)
  3. 33 Past Simple: Negatives and Questions (did)
  4. 34 Comparative Adjectives (bigger, more expensive)
  5. 35 Superlative Adjectives (the biggest, the most)
  6. 36 Going To: Plans and Predictions
  7. 37 Will: Predictions, Decisions and Offers
  8. 38 Present Continuous for Future Arrangements
  9. 39 Present Perfect for Experience (ever / never)
  10. 40 Present Perfect with just, already, yet
  11. 41 Present Perfect vs Past Simple
  12. 42 Have To and Don't Have To (Obligation)
  13. 43 Should and Shouldn't for Advice
  14. 44 Could: Past Ability and Polite Use
  15. 45 Much, Many, A Lot Of
  16. 46 A Few, A Little, Few, Little
  17. 47 Adverbs of Manner (quickly, well, hard)
  18. 48 Verb + -ing or Verb + to (Introduction)
  19. 49 Zero Conditional (Facts and Rules)
  20. 50 First Conditional (Real Future Possibility)
  21. 51 Prepositions of Movement (to, into, through)
  22. 52 Possessive Pronouns: mine, yours, hers
  23. 53 Past Continuous (was/were + -ing)
  24. 54 Too and Enough (Degree)
  25. 55 Order of Adjectives Before a Noun
B1 27 topics · 27 ready
  1. 56 Past Continuous vs Past Simple
  2. 57 Used To and Would for Past Habits
  3. 58 Present Perfect Continuous (have been -ing)
  4. 59 Present Perfect: Simple vs Continuous
  5. 60 Past Perfect (had + past participle)
  6. 61 Second Conditional (Unreal Present/Future)
  7. 62 Third Conditional (Unreal Past)
  8. 63 Reported Speech: Statements (Backshift)
  9. 64 Reported Questions
  10. 65 Reported Commands and Requests
  11. 66 Passive Voice: Present and Past Simple
  12. 67 Must and Mustn't (Strong Obligation)
  13. 68 May, Might, Could for Possibility You are here
  14. 69 Defining Relative Clauses (who, which, that)
  15. 70 Non-Defining Relative Clauses (with commas)
  16. 71 Gerunds and Infinitives: Full Verb Patterns
  17. 72 Verbs Where -ing vs to Changes Meaning
  18. 73 Future Continuous (will be -ing)
  19. 74 So and Such (Emphasis)
  20. 75 As...As Comparisons (equality)
  21. 76 Question Tags (isn't it? do you?)
  22. 77 Phrasal Verbs: Separable and Inseparable
  23. 78 Linking Words: because, so, although, but
  24. 79 Infinitive of Purpose (to / in order to)
  25. 80 Indirect Questions (Can you tell me...)
  26. 81 Make, Let, Allow, Help (Causatives Intro)
  27. 82 Be Used To and Get Used To (+ -ing)
B2 25 topics · 25 ready
  1. 83 Narrative Tenses for Storytelling
  2. 84 Past Perfect Continuous (had been -ing)
  3. 85 Mixed Conditionals
  4. 86 Wish and If Only (Regrets and Wishes)
  5. 87 Wish/If Only + would (Complaints)
  6. 88 Passive Voice: All Tenses and Modals
  7. 89 Reporting Passive (It is said that / is said to)
  8. 90 Causative: Have/Get Something Done
  9. 91 Reduced Relative Clauses (Participles)
  10. 92 Modals of Deduction: Present and Past
  11. 93 Needn't Have vs Didn't Need To
  12. 94 Future Perfect (will have done)
  13. 95 Participle Clauses (-ing / -ed / having done)
  14. 96 Advanced Comparatives (far/much + er, the more)
  15. 97 Conditional Alternatives: unless, as long as, provided
  16. 98 Advanced Determiners: each, every, either, neither
  17. 99 Intensifiers and Adverbs of Degree
  18. 100 Advanced Contrast: despite, in spite of, however
  19. 101 Advanced Linkers: therefore, moreover, consequently
  20. 102 Advanced Article Use (generalisations, names)
  21. 103 Verb + Preposition and Adjective + Preposition
  22. 104 Relative Clauses: whose, where, when, quantifier + whom
  23. 105 Subject-Verb Agreement: Tricky Cases
  24. 106 Emphatic Do (I do like it)
  25. 107 Would for Past Habits (Formal Narrative)
C1 18 topics · 18 ready
  1. 108 Inversion with Negative Adverbials
  2. 109 Inversion in Conditionals (Had I known)
  3. 110 Cleft Sentences (It was... / What I need is...)
  4. 111 Fronting and Emphasis (Word Order)
  5. 112 Subjunctive and Mandative (I suggest he be)
  6. 113 Ellipsis and Substitution (so, do, one)
  7. 114 Hedging and Cautious Language
  8. 115 Nominalisation (Academic Noun Style)
  9. 116 Advanced Discourse Markers (Spoken & Written)
  10. 117 Advanced Passive (passive + infinitive, get-passive)
  11. 118 Advanced Comparative Structures (no sooner...than)
  12. 119 Future in the Past (was going to / would)
  13. 120 Advanced Modals (may well, might as well, would rather)
  14. 121 Advanced Reported Speech (Reporting Verbs + Patterns)
  15. 122 Advanced and Idiomatic Phrasal Verbs
  16. 123 Collocation and Colligation (Natural Combinations)
  17. 124 Advanced Concession (much as, whatever, however + adj)
  18. 125 Absolute and Non-Finite Clauses (Formal)