It is 11:40 p.m. and Hina is drafting an email to her professor. She types, “I might submit the assignment on Monday” — then stops. Does that sound like a polite request, or like she is only half-promising to submit at all? She deletes it, types “May I submit the assignment on Monday?” — and now it reads like she is asking permission she does not actually need. Two tiny modal verbs, two completely different emails. Here is the system that keeps them straight.
May vs Might: The Short Answer
British Council LearnEnglish teaches “may” for (a) uncertainty about the present or future and (b) formal permission, and “might” for (a) uncertainty about the present or future, (b) the past tense of “may” in reported speech, and (c) very polite requests — while Microsoft 365’s writing guide adds that “may” signals a more likely outcome than “might,” and that in American English “might” is never used for permission. Put simply: may = permission plus stronger possibility; might = weaker possibility plus the past of may.
The Three-Way Split
Every may/might question resolves on three axes: permission, possibility, and tense. Check which axis your sentence lives on, and the answer is mechanical. This pair is the modal-verb cousin of other eternal English mix-ups — hanged vs hung, this batch’s sibling article, works the same way: one clean system underneath a messy-looking pair. Take the axes one at a time.
Axis 1: Permission → “May” Only
Formal permission belongs to “may,” full stop. “May I borrow the car?” “You may go now.” “Students may not use phones during the exam.” The British Council lists permission as a core may-function, and Microsoft 365 is explicit: in American English, “might” is never used to grant or refuse permission.
What about “Might I ask you a question?” That is the British Council’s third might-use — a very polite, very formal request formula — and it is a courtesy wrapper, not a permission grant. It survives in period dramas and formal British correspondence. In ordinary American usage, asking permission with “might” will sound like you are doing a Jane Austen impression.
Axis 2: Possibility → “May” Is Stronger
Both words handle uncertainty about the present or future. “Jack may be coming to see us tomorrow.” “I might see you tomorrow.” Same job, different dial setting: “may” signals that the speaker judges the outcome more likely; “might” pushes it further away, more remote, more doubtful.
Think of it as a confidence slider. “We may get the contract” leans toward yes — the speaker sees real grounds for it. “We might get the contract” sits at genuinely 50/50, or even leans no. In casual speech the line blurs and native speakers swap them freely, but in careful writing the distinction reads: choose “may” when you want the possibility to sound plausible, “might” when you want it to sound distant.
Axis 3: Tense → “Might” as the Past of “May”
In reported speech, a past-tense main clause backshifts “may” to “might.” Direct: “He said, ‘I may borrow the car.'” Reported: “He asked if he might borrow the car.” The request was present-tense “may” in his mouth; by the time we report it, the moment has passed, and “might” marks that shift.
This is the one axis where “might is the past of may” is literally true — and it is the source of the myth dismantled below.
“May Have” vs “Might Have”
Move the possibility dial into the past and you get “may have” and “might have” — guesses about what already happened. The likelihood rule carries over unchanged: “She may have left already” sounds fairly confident (the keys are gone, the lights are off); “She might have left already” sounds noticeably more doubtful. Same structure, same slider, one tense earlier.
The Myth to Drop
The myth goes: may = present, might = past, always. It is wrong, and it is the single most common thing learners get told about this pair. Both “may” and “might” can describe present or future possibility — the British Council lists exactly that use (“not sure about something in the present or future”) for both words. “I may see you tomorrow” and “I might see you tomorrow” are both about tomorrow.
“Might” is the past of “may” only in reported speech. English has a whole family of these stubborn mix-ups that survive because the memorized slogan is simpler than the system — then vs than and each vs every persist for the same reason. The slogan (“might is past”) is a fragment of the truth; the three-axis system is the truth.
Quick Practice
Choose “may” or “might” for each blank. Answers follow.
- ___ I use your phone for a minute? (asking permission)
- It ___ rain later, so take an umbrella. (fairly likely)
- She ___ come to the party, but she hasn’t decided. (genuinely uncertain)
- He said he ___ call back soon. (reported speech)
- ___ I ask you a small favor? (very polite request)
- They ___ have finished the report by now. (a weak guess about the past)
Answers: 1. May — permission belongs to may, never might in American English. 2. may — the stronger-likelihood setting. 3. might — weaker, more remote possibility. 4. might — backshifted past of may in reported speech. 5. Might — the very-polite-request formula. 6. might have — the weaker guess about the past.
Frequently Asked Questions
“May” handles permission and stronger possibility; “might” handles weaker possibility and serves as the past tense of “may” in reported speech. Microsoft 365’s writing guide puts the likelihood point plainly: may signals a more likely outcome than might.
Not in American English — Microsoft 365 is explicit that might is never used to grant or ask permission there. Use “may”: “May I borrow the car?” A very polite “Might I ask you a question?” exists in formal British style, but it is a courtesy formula, not permission.
Only in reported speech: “He asked if he might borrow the car.” For present or future possibility, both may and might work — “I may/might see you tomorrow” — so don’t treat might as always-past.
For requests, “might” is the more formal and tentative option: “Might I ask you a question?” For permission, “may” is the standard: “May I come in?”
Both guess about the past; “may have” sounds more confident (“She may have left already”), “might have” more doubtful (“She might have left already”). Same likelihood dial, one tense earlier.
Often in casual speech, yes — the likelihood difference is a dial, not a wall. But they are not interchangeable for permission (may only) or reported speech (might only). In careful writing, keep the three axes apart.
