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May vs Might — What’s the Difference?

May expresses a higher likelihood or asks for permission. Might suggests a lower probability or a hypothetical situation. The key difference: may signals something that is reasonably possible, while might signals something less certain or purely speculative. Many speakers use them interchangeably in casual conversation, but careful writers distinguish between the two to convey precise degrees of probability.

Why Getting This Right Matters

Mixing up may and might is one of the most common modal verb errors in professional English writing. In a cover letter, writing “I may have led a team of ten” when you mean “I might have led a team” sends a confusing signal — did you lead the team or not? In academic papers, using may where might is required can misrepresent the certainty of your findings. And in business emails, writing “the shipment may have arrived” when it definitely has not yet arrived creates ambiguity that wastes your reader’s time and erodes trust in your communication.

What Does “May” Mean?

The modal verb may serves two primary functions in English. First, it expresses possibility with a relatively high degree of likelihood. When someone says “It may rain this afternoon,” they are suggesting a genuine chance of rain, perhaps around 50 percent or higher. Second, may is used to grant or request permission. “May I leave the table?” is the classic polite request that grammar teachers have championed for generations.

In formal writing, may carries authority. Legal documents, scientific papers, and policy statements often use may to describe what is permitted or plausible. “The applicant may submit additional documentation” means the applicant has permission to do so. This dual role of possibility and permission makes may one of the most versatile modal verbs in English.

Historically, may comes from Old English magan, meaning “to be able” or “to have power.” Over centuries, it shifted from expressing ability, a role now filled by can, to expressing possibility and permission. Understanding this evolution helps explain why may still carries a sense of openness and potential.

Style guides treat may with particular attention. The AP Stylebook explicitly recommends distinguishing may from might based on probability. Garner’s Modern English Usage rates the interchangeable use of may and might as a Stage 3 error — widely encountered but still considered a lapse by informed writers. In scientific writing, may is the standard choice for describing established possibilities: “Exposure to UV radiation may cause skin damage” states a known risk, while “might” would inappropriately weaken the claim.

What Does “Might” Mean?

Might is the past tense form of may, but in modern English it functions primarily as a modal verb expressing lower probability or hypothetical situations. When someone says “I might go to the party,” the implication is that attendance is uncertain, perhaps a 30 percent chance or less. The speaker is leaving significant room for the possibility of not going.

Might also appears in counterfactual statements, describing things that did not happen. “If you had asked me, I might have agreed” refers to a past situation that never occurred. In this role, might cannot be replaced by may without changing the meaning or creating ambiguity. This distinction is where the may-vs-might difference matters most.

Additionally, might softens suggestions and requests. “You might want to double-check that figure” is gentler than “You may want to double-check that figure.” The extra tentativeness makes might useful in diplomatic communication, where directness could seem confrontational. British English tends to use might more frequently in these polite, hedging constructions.

Key Differences Between May and Might

Degree of probability. This is the most important distinction for everyday use. May suggests something is fairly likely. Might suggests it is less likely. “The project may be finished by Friday” sounds optimistic. “The project might be finished by Friday” sounds doubtful. Choosing the right word lets you calibrate your reader’s expectations.

Past possibilities that did not happen. When describing an event that could have occurred but did not, might is the correct choice. “He might have survived if the ambulance had arrived sooner” refers to an unrealized past outcome. Using may here, “He may have survived,” creates ambiguity because it could mean his survival is still unknown. This is one case where the distinction is not optional.

Permission. May is the standard word for granting or requesting permission. “You may begin the exam” is something a teacher says; “You might begin the exam” sounds odd in that context. Might is occasionally used for very tentative permission requests, “Might I have a word?” but this is formal to the point of being old-fashioned.

Tense and sequence. In reported speech and past-tense narratives, might naturally replaces may. Direct: “I may visit London.” Reported: “She said she might visit London.” This follows the standard backshift pattern of English modal verbs.

Grammatical category. This is a modal verb distinction — specifically, a difference in epistemic modality (the degree of certainty a speaker expresses about a proposition). Both may and might are modal auxiliaries derived from the same Old English root magan, but they diverged as might became the past tense form and gradually acquired a distinct present-tense function signaling reduced probability. The confusion is amplified because many languages — including Spanish, Mandarin, and Arabic — use a single modal construction for all degrees of possibility, leaving no intuitive framework for distinguishing may from might. Garner’s Modern English Usage classifies the interchangeable use of these modals as a Stage 3 error: widespread but still considered a lapse in careful prose.

Formality. Both words are appropriate in formal and informal contexts, but might often feels slightly more tentative and polite, while may can carry a tone of authority, especially in the permission sense.

May vs Might — Examples in Context

Correct: We may get a bonus this quarter. (The speaker believes it is fairly likely.)

Correct: We might get a bonus this quarter. (The speaker is less confident.)

Correct: May I borrow your pen?

Awkward: Might I borrow your pen? (Overly formal for most situations.)

Correct: If I had studied harder, I might have passed the exam.

Incorrect: If I had studied harder, I may have passed the exam. (Creates ambiguity about whether the result is still unknown.)

Correct: The train may be delayed due to weather. (Likely delay.)

Correct: The train might be delayed if the storm gets worse. (Conditional, less certain.)

Correct: She said she might join us for dinner. (Reported speech.)

Incorrect: She said she may join us for dinner. (Fails to backshift the tense in reported speech.)

Correct: You might want to reconsider that approach. (Polite suggestion.)

Correct: The medication may cause drowsiness. (Official medical language; genuine possibility.)

Correct: The medication might cause drowsiness in rare cases. (Lower probability.)

Professional email: “The client may request a revised timeline, so please have one ready.” ✓

Common mistake: “If the client had asked last week, we may have accommodated the change.” ✗ (Use might — the opportunity has passed; this is a counterfactual.)

Academic writing: “Further research may reveal additional correlations between the variables.” ✓

Common mistake: “Had the sample size been larger, the study may have produced significant results.” ✗ (Use might — the study is complete and the larger sample was never collected.)

Job application: “This role may involve occasional travel to regional offices.” ✓

Casual/social media: “I might go to the concert tonight — depends on whether I can get tickets.” ✓

Common Mistakes and How to Avoid Them

The biggest mistake is using may for past counterfactuals. “If the road had been clear, we may have arrived on time” should use might because the event did not happen. Using may creates ambiguity about whether you actually arrived on time or not. When referring to outcomes that definitely did not occur, always choose might.

Another error is treating the two words as perfectly interchangeable in written contexts where precision matters. In speech, the overlap is forgivable. In a research paper or business proposal, the difference between “sales may increase” and “sales might increase” sets different expectations for your reader.

Some writers also confuse may as permission with can as ability. “Can I leave early?” asks about ability; “May I leave early?” asks about permission. While this distinction is fading in informal English, maintaining it in professional contexts shows grammatical awareness. A tool like BeLikeNative can help flag these subtle modal verb issues.

The #1 mistake pattern. The error occurs most frequently in sentences beginning with “If + past perfect” — structures like “If she had known, she may have…” The conditional had known signals an unrealized past scenario, which demands might, not may. Whenever you see “if + had,” reach for might.

The exception that proves the rule. In some legal and scientific writing, may have is used even for past events when the outcome is genuinely unknown: “The suspect may have fled the country” is correct if investigators do not yet know. This is not a counterfactual — it is an open question, and may is appropriate.

Non-native speakers face an additional challenge because many languages lack a direct equivalent to the may/might probability distinction. In Spanish, French, and German, a single modal construction covers both degrees of possibility, so learners must actively train themselves to choose between may and might based on how likely an outcome is. A practical exercise is to assign rough percentages: if you would rate the chance above 40 percent, lean toward may; below that threshold, choose might.

Quick Memory Trick

May = Maybe (lean yes, 50%+ chance). Might = Slight (lean no, slim chance). Both words contain their probability clue. And for past events: if the door is closed and the outcome is sealed, use might — because only a slight twist of fate could have changed it. “He might have won” = he lost. “He may have won” = we do not know yet.

Related Confused Word Pairs

Explore more commonly confused words to sharpen your grammar:

• Immigrate vs Migrate — two movement verbs with different scopes and connotations.
• Any Way vs Anyway — spacing matters more than you think.
• Grammer vs Grammar — the ironic misspelling of a word about correct spelling.

FAQ

Are may and might interchangeable?
In casual speech, they often are. In careful writing, they convey different degrees of probability. May signals higher likelihood; might signals lower likelihood or hypothetical situations.

Should I use may or might for past events?
If the event did not happen, use might. “She might have caught the train if she had left earlier” is correct because she missed it. Using may would imply you still do not know whether she caught it.

Is “may” more formal than “might”?
Not exactly. Both are standard in formal writing. However, may often carries more authority, especially in the permission sense, while might sounds more tentative and polite.

Can “might” be used for permission?
Technically yes, but it sounds old-fashioned. “Might I have a moment of your time?” is grammatically correct but very formal. In modern English, may is the standard choice for permission.

What about “may have” vs “might have”?
“She may have left already” means you are uncertain whether she left. “She might have left if she had known” refers to a hypothetical past scenario. The distinction is about whether the outcome is unknown (may have) or unrealized (might have).