May vs. Might
May and might both express possibility and often overlap. Might can sound more tentative in many contexts, but a rigid certainty percentage is unreliable; tense, reported speech and speaker stance can also affect the choice.
Both may and might can express possibility. Might is often more tentative, but do not treat them as a fixed probability scale in every context.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| present/future possibility | may or might | Both can be standard; “might” can sound more tentative. |
| permission in ordinary formal usage | may | “May” can express permission; “might” is not a simple interchangeable permission form. |
| reported/hypothetical contexts | might | “Might” can also reflect backshift or hypothetical framing. |
Quick tests
Meaning / construction test
Are you merely expressing possibility rather than permission or a tense/hypothetical contrast?
If yes: Either may fit; use context and stance, not a fixed probability percentage, to choose.
If no: Check whether permission, reported speech, or hypothetical framing makes one form more appropriate.
Caveat: Do not assign rigid certainty percentages to “may” and “might”; overlap is substantial and context matters.
Examples
It may rain later.
“May” expresses possibility.
It might rain later.
“Might” also expresses possibility and can sound more tentative.
You may leave once the test is complete.
Here “may” expresses permission rather than a probability level.
Further guidance
Grammar Boundary
Might also appears in backshifted and hypothetical structures where simple substitution with may can change the construction.
Possibility Boundary
May and might overlap heavily for possibility; context and speaker stance matter.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Could, may and might — Cambridge Grammar (opens in a new tab)Cambridge Dictionary · May and might for possibility, including uncertainty about fixed certainty rankings