May and might are close relatives. Both express possibility: "It may rain" and "It might rain" are both correct and mean almost the same thing. The difference is confidence and tone, not grammar.
May also borrows a second job: permission. "May I sit here?" is formal and polite. Might does not ask permission in modern English, but it does make gentle suggestions: "You might want to check the timetable."
This page explains the confidence gap, the permission use, the past forms with have, and the patterns with not. The 20-question drill checks each use with a short rule explanation.
The rule
Possibility: the confidence gap
- Both may and might mean that something is possible, but not certain: "She may be at home", "She might be at home."
- May suggests a slightly stronger chance; might suggests it is less likely or more remote.
- The two verbs are usually interchangeable, so no test answer is wrong just because it chose might over may.
- Do not add to after either verb: "It may rain", not "It may to rain."
May for permission
- May asks and gives permission in a formal or polite way: "May I open the window?"
- You may not is the formal refusal: "You may not park on this street."
- In everyday speech, can is more common for permission. May sounds more careful and formal.
- Permission answers often drop the verb: "May I go?" — "Yes, you may" or "No, you may not."
Might for suggestions and requests
- Might makes a very polite suggestion: "You might try the soup."
- Could sometimes replaces might in suggestions, while may does not work there.
- Might I ask a question? is extremely formal and rare, but it shows the polite edge of the word.
- Might also softens a complaint: "You might have told me earlier."
Past possibility with have
- May have and might have plus the past participle describe possibilities in the past: "He may have left already."
- Might have is also used for unrealised possibilities and gentle reproach: "You might have warned me."
- Both forms are common in speculation: "She might have missed the bus."
- For a certain deduction, use must have; for impossibility, use cannot have.
May not and might not
- May not can mean two things: not permitted, or possibly not true. Context decides.
- Might not only talks about possibility: "It might not work."
- In negatives, might not sounds more naturally uncertain than may not.
- The past negatives are may not have and might not have plus the participle.
Examples
- It may rain this afternoon.A real possibility with a slightly stronger chance.
- It might rain this afternoon.The same idea with more doubt or distance.
- May I use your phone for a minute?A formal request for permission.
- You may not swim here; the water is dangerous.A formal refusal of permission.
- You might want to bring a jacket.A gentle suggestion with might.
- He may have left already; his coat is gone.Past possibility with may have plus the participle.
- She might have taken the wrong train.A past possibility with less certainty.
- You might have told me the meeting was cancelled.Might have softens a complaint about a past action.
- We may not have enough chairs for everyone.May not expresses a possible negative situation.
- It might not snow after all.Might not looks at an uncertain future.
Common mistakes
- Wrong: It may to rain later. Right: It may rain later.
- Modals take the base verb without to. May and might never use to.
- Wrong: May you help me with this box? Right: Could you help me with this box?
- May asks for permission, not for help. Requests for action use could or would.
- Wrong: He may have went home. Right: He may have gone home.
- After have in a perfect form, the past participle is required: gone, not went.
- Wrong: She might stays at home tonight. Right: She might stay at home tonight.
- Might is a modal, so the next verb stays in the base form.
- Wrong: You might to be tired after the trip. Right: You might be tired after the trip.
- Might takes the base verb directly, with no to and no extra verb.
Practice drill
Answer all 20 questions. Each answer is marked at once, and the rule is explained under the question.
It ___ rain this afternoon, so take an umbrella.
Show answer and explanation
Answer: A. may May expresses a future possibility and takes the base verb rain without to.
She ___ be at home; her lights are on.
Show answer and explanation
Answer: B. may May expresses a present possibility, followed directly by the base verb.
___ I open the window, please?
Show answer and explanation
Answer: C. May May asks for permission in a formal and polite way.
You ___ not park on this street; it is forbidden.
Show answer and explanation
Answer: D. may May not gives a formal refusal of permission.
You ___ want to check the timetable before you leave.
Show answer and explanation
Answer: A. might Might makes a gentle suggestion, which fits the friendly advice.
He ___ have left already; his coat is gone.
Show answer and explanation
Answer: B. may May have plus the past participle left describes a past possibility.
She ___ have taken the wrong train.
Show answer and explanation
Answer: C. might Might have plus the participle expresses a less certain past possibility.
You ___ have told me that the meeting was cancelled.
Show answer and explanation
Answer: D. might Might have softens a complaint about a past action.
We ___ not have enough chairs for everyone.
Show answer and explanation
Answer: A. may May not expresses a possible negative situation in the present.
It ___ not snow after all; the sky is clearing.
Show answer and explanation
Answer: B. might Might not looks at an uncertain future possibility.
Which sentence is correct?
Show answer and explanation
Answer: C. It may rain later. May takes the base verb without to: It may rain later is the correct modal pattern.
___ you pass me the salt, please?
Show answer and explanation
Answer: D. Could A request for help uses could, because may asks for permission.
He ___ have gone home; his desk is empty.
Show answer and explanation
Answer: A. may May have plus the participle gone expresses a present guess about the past.
She might ___ at home tonight.
Show answer and explanation
Answer: B. stay Might is a modal, so the base form stay follows it directly.
You may ___ here if you buy a ticket.
Show answer and explanation
Answer: C. park May for permission takes the base verb park without to.
I ___ finish the report tonight, but I am not sure.
Show answer and explanation
Answer: D. may May expresses an uncertain possibility about the future.
Customers ___ ask for a refund within 30 days.
Show answer and explanation
Answer: A. may May states formal permission in a written policy.
That ___ be true; it sounds impossible.
Show answer and explanation
Answer: B. may not May not expresses the possibility that something is not true.
It is late. She ___ have forgotten the appointment.
Show answer and explanation
Answer: C. might Might have plus the participle forgotten expresses a past possibility.
Guests ___ use the garden during the day.
Show answer and explanation
Answer: D. may May gives formal permission, followed by the base verb use.
Drill complete
You answered every question.
Next topic: Phrasal verbs with up: finish, increase, arriveTake the level test
Questions learners ask
Are may and might exactly the same?
They overlap so much that most sentences accept both. The old idea that may is a bigger possibility than might is only a tendency, not a rule. Choose may for a formal or slightly more confident tone, and might for a softer or more doubtful one.
Why is "May I" more polite than "Can I"?
May asks for permission directly and carries a formal tone. Can asks about ability and possibility, so it sounds more casual. Both are correct in daily life, but may suits teachers, offices and formal situations.
What is the difference between "may have" and "might have"?
Both describe past possibilities. May have suggests the chance was slightly stronger at the time. Might have has a second use: it can criticise something that did not happen, as in "You might have called." That reproach reading belongs almost entirely to might.
More grammar topics
Phrasal verbs with up: finish, increase, arrive
The particle up often means completely, higher or appearing. Learn the verbs in meaning groups instead of one long list.
Separable or inseparable phrasal verbs
A noun object can often move, but a pronoun cannot. It must sit between the verb and the particle in a separable phrasal verb.
Reported questions: word order and tense
A reported question stops being a question. It takes statement word order, drops the auxiliary, and often moves one tense back.
Take the free A1 to C2 level test to find your starting point.