Quick answer: May suggests a higher probability of something happening. Might suggests a lower probability or more doubt. In informal conversation they are often interchangeable, but in formal English the distinction matters. For a fuller definition, see the Cambridge Dictionary entry for ‘may’.
Comparison Table
| Word | Part of Speech | Key Meaning | Example |
|---|---|---|---|
| may | modal verb | higher probability (~50%+) | It may rain this afternoon. |
| might | modal verb | lower probability / more doubt | It might rain, but I doubt it. |
Using May
Use may when there is a reasonable or fairly good chance that something will happen. It expresses possibility with a degree of confidence. May is also the standard modal for asking or giving permission in formal English.
It may rain this afternoon. (fairly likely — the sky looks dark)
She may be late — she usually is.
He may be able to help us — he knows this area well.
You may leave as soon as you finish the test. (permission)
May for Permission
In formal contexts, may is the traditional way to ask for or grant permission. It is preferred in official, academic, and polite speech over the more casual “can”.
May I come in?
Students may use dictionaries during the exam.
Using Might
Use might when something is possible but you have significant doubt, or when the chance feels low. Might also functions as the past tense of may in reported speech, and is used in polite or tentative suggestions.
It might rain. (less certain than “may rain”)
I’m not sure, but she might have left already.
You might want to reconsider before signing. (gentle suggestion)
He might come, but I’m not sure.
Might in Reported Speech
When turning direct speech into reported speech, might is the past form of may.
Direct: “I may be late,” she said.
Reported: She said she might be late.
Might Have — Speculation about the Past
Both might have and may have are used to speculate about past events. “Might have” carries more doubt.
She might have left already. (less certain)
She may have left — it’s getting late. (slightly more likely)
Common Mistakes
✗ There might be significant consequences. (if the risk is considered quite high)
✓ There may be significant consequences. (higher likelihood; correct in formal warnings)
Note: in casual speech the difference is minor, but in formal or legal English, use may for higher probability.
✗ Might I use your phone? (grammatically fine but sounds very old-fashioned)
✓ May I use your phone? (natural and polite in modern English)
✗ He said he may join us later. (mixes tenses in reported speech)
✓ He said he might join us later. (correct backshift in reported speech)
Tips to Remember
- More likely? Use may. Less sure? Use might.
- Think of might as “may + extra doubt”.
- For permission, stick with may in formal English.
- In reported speech, shift may → might automatically.
- In everyday conversation, either word is usually fine — native speakers rarely notice the difference.
Also confusing: Can vs Could. Browse all confusing word pairs →
Quick Check: May or Might?
Four fill-in-the-blank questions — choose the best word for each sentence.
1. “I’m not sure, but she ___ have left already.”
2. “It looks cloudy. It ___ rain later.”
3. “You ___ want to reconsider before signing.”
4. “He ___ be able to help us — he knows this area well.”
Frequently Asked Questions
What is the difference between may and might?
May suggests a higher probability that something will happen (around 50% or more), while might suggests a lower probability or greater uncertainty. In informal speech they are often interchangeable, but in formal English the distinction is preserved.
Is might more uncertain than may?
Yes. Might implies more doubt or a smaller chance than may. “It may rain” suggests rain is fairly likely; “it might rain” suggests it is possible but less certain.
Can may and might be used interchangeably?
In casual conversation, most native speakers treat them as interchangeable. In formal writing or when precision matters — such as legal, academic, or journalistic texts — the distinction between higher probability (may) and lower probability (might) is worth preserving.
When should I use may?
Use may when there is a fairly good chance something will happen: “She may be late — she usually is”, “It may rain this afternoon”, “He may be able to help us”. May is also used to ask for or give permission in formal contexts: “May I come in?”
When should I use might?
Use might when something is possible but you have significant doubt: “I’m not sure, but she might have left already”, “You might want to reconsider before signing”, “He might come, but I’m not sure”. Might is also the past tense of may in reported speech.
Is “might” the past tense of “may”?
Historically yes. In reported speech, might is used as the past form of may: “She said she might be late” (direct: “I may be late”). In modern English, might also exists as an independent modal expressing low probability in the present or future.
Can I use “may” to ask for permission?
Yes. May is the formal and traditionally correct way to request permission: “May I borrow your pen?” Using might for permission (“Might I borrow your pen?”) sounds very formal or old-fashioned, though it is grammatically acceptable.
What is “might have” used for?
“Might have” is used to speculate about past events: “She might have left already” (you are not sure whether she left). “May have” carries the same meaning but suggests slightly higher certainty: “She may have left — it’s getting late.”
Do may and might differ in formal writing?
Yes. In formal English — legal documents, academic papers, and formal journalism — may is reserved for higher probability and might for lower probability. This distinction can affect meaning, so careful writers maintain it.
How do may and might appear in IELTS or TOEFL?
In IELTS and TOEFL, modal verbs are tested for meaning and register. May is common for possibilities with reasonable likelihood; might is used for speculative or less certain ideas. Using them accurately demonstrates a strong command of modal nuance and improves your grammar score.