May and might both express possibility, and for everyday guesses they are often interchangeable — it may rain and it might rain mean much the same thing. The differences that genuinely matter are two: use might for hypothetical or imagined situations, and use might have (not may have) for a past event that did not actually happen. The traditional idea that may means 'more likely' and might means 'less likely' is a real tendency, but a weak one — not a rule worth agonising over.
Plenty of style guides teach that 'may' signals a stronger possibility and 'might' a more remote one. There is a grain of truth in it: We may finish today can sound a touch more confident than We might finish today. But the effect is subtle, and most fluent speakers treat the two as interchangeable when talking about possibility. Don't lean on the distinction to carry important meaning — if you need to show how likely something is, say so directly with words like 'probably' or 'there's a slim chance'. And note that both 'may' and 'might' can point to the present or the future, so 'might' is not somehow weaker or more childish English:
Historically, 'might' is the past tense of 'may', and that job survives mainly in reported (indirect) speech, where a present-tense 'may' shifts back to 'might':
Modern usage also lets you keep 'may' when the possibility is still open (She said she may be late), but 'might' is the traditional, always-safe choice. Here 'might' isn't really describing a past event — it's just a change of form.
This is where the two words part company cleanly. For imagined or contrary-to-fact situations — the kind introduced by second- and third-conditional 'if' — use 'might', never 'may':
Keep 'may' for real, open conditions, where the outcome is still genuinely on the table:
Both 'may have' and 'might have' can express uncertainty about the past. When you honestly don't know what happened, they're interchangeable:
The difference bites when the event did not happen. For a past possibility that never came true — a near miss, a lucky escape, a what-if — you need 'might have'. 'May have' is wrong there, because it implies the outcome is still open, that perhaps it did occur:
Set the two meanings side by side and you can see why:
Because 'may have' can't clearly signal 'and it didn't', careful writers default to 'might have' whenever the thing described never actually occurred. This is the single most useful may/might distinction in English — and the one newspapers most often get wrong.
'Might' is the past tense of 'may', so give it every job that sits one step away from plain reality: the past, the hypothetical, and the thing that didn't happen. Distance in form mirrors distance in fact. For the past specifically, remember: might have = it might have, but it didn't; may have = maybe it actually did.
Barely. The rules above hold on both sides of the Atlantic — the 'might have' counterfactual, the reported-speech shift, and the fading likelihood distinction are all shared, and the 'may have' slip in near-miss sentences turns up in American and British journalism alike. The only mild regional flavour is that 'Might I…?' for permission, and heavily hedged 'might', sound more characteristically British and formal, while American English leans a little harder on 'may' and 'can'. Anyone who tells you 'Americans always say may, Britons always say might' is overselling a difference that isn't really there.
Both are correct, but they differ. Use 'might have' for something that did not happen — 'You might have been hurt!' (you weren't). Use 'may have' when the past outcome is genuinely unknown — 'She may have missed the train.' For a near miss or lucky escape, always choose 'might have'; 'may have' hints the thing possibly did occur.
Traditionally yes — 'may' suggests a stronger possibility and 'might' a more remote one. In practice the difference is slight, and most speakers use the two interchangeably for possibility, with 'might' sounding a touch more tentative. Don't rely on it to carry weight; if likelihood matters, state it plainly with 'probably' or 'a slim chance'.
Historically 'might' is the past tense of 'may', and that role survives in reported speech: 'I may be late' becomes 'She said she might be late.' But 'might' is not limited to the past — it freely describes present and future possibility ('I might go tomorrow') and hypothetical situations ('I might, if I could').
Yes, in real, open conditions where the outcome is still possible: 'If you hurry, you may catch the train.' But for unreal or imagined conditions — second and third conditionals — use 'might': 'If I had time, I might learn Italian,' or 'She might have said yes if you'd asked.' Using 'may' there sounds wrong.
Often, yes. Because 'might' is more tentative, requests like 'Might I make a suggestion?' sound softer and more deferential than 'May I?' — and distinctly formal or British. For everyday permission, 'May I…?' is the neutral standard, while 'Can I…?' is the relaxed, conversational choice most people actually use.
