Why can both It may rain tonight and It might rain tonight be correct? The common explanation that may means “more likely” and might means “less likely” sounds simple, but it does not explain how these modal verbs actually work.
For ordinary possibility, may and might often overlap. The clearer differences appear in uses such as permission, tentative suggestions, hypothetical situations, reported speech, and unrealized past possibilities.
May vs. Might: What Is the Difference?
Both may and might are modal verbs, and both can express uncertainty about the present or future.
Elena may join us later.
Elena might join us later.
Both sentences mean that Elena’s joining is possible but not certain.
In many contexts, the difference is small. Might can sometimes sound more tentative, cautious, or remote, but that is a tendency rather than a fixed rule about probability.
The two forms become easier to distinguish when other uses are involved.
May has an established role in permission:
May I come in?
Might is especially common in tentative suggestions and more remote or hypothetical situations:
You might want to check the address again.
If I had more free time, I might travel more.
So the difference is broader than simply “more certain” versus “less certain.”
Do May and Might Show Different Levels of Certainty?
Sometimes might sounds more tentative than may.
Compare:
The delivery may arrive this afternoon.
The delivery might arrive this afternoon.
A speaker may choose might to sound more cautious or less committed to the prediction.
But English does not assign the two modals fixed levels of probability.
It is therefore misleading to teach rules such as:
may = likely
might = unlikely
or:
may = 50%
might = 30%
In many ordinary sentences about possibility, either form is natural.
Context, tone, type of possibility, and the speaker’s attitude all influence the choice.
Using May and Might for Present Possibility
Both verbs can describe something that may be true now.
Noah may be in his office.
Priya might know the answer.
The keys may be in the kitchen drawer.
Daniel might be waiting outside.
Neither modal automatically refers to past time.
They can also appear with progressive structure when the possible situation is ongoing:
Maya may be working upstairs.
Leo might be sleeping.
Here, may and might express uncertainty, while be + -ing presents the activity as in progress.
Using May and Might for Future Possibility
Both are also common for uncertain future events.
The company may announce the changes tomorrow.
We might visit Edinburgh next summer.
The road may reopen by Friday.
Ava might stay for another week.
Sometimes the two can be exchanged with little change in meaning:
The meeting may finish early.
The meeting might finish early.
The second sentence can sound slightly more tentative, but it does not automatically mean the event is much less likely.
When Might Sounds More Tentative
Might is particularly natural when a speaker wants to keep an idea open or avoid sounding definite.
I might take Friday off.
The plan is not settled.
We might need a larger room.
The need is only a possibility.
Maya might join us if she finishes work early.
The outcome depends on another condition.
This tentative quality helps explain why might appears so naturally in suggestions and hypothetical situations.
Using May for Permission
One of the clearest differences between the two verbs is permission.
May can be used to ask for permission:
May I use your phone?
May we enter now?
It can also grant permission:
You may leave when you have finished.
Visitors may use the side entrance.
This use can sound formal or polite.
In everyday conversation, can is also extremely common:
Can I sit here?
But may remains a standard choice, particularly in formal, careful, or official contexts.
Can Might Be Used for Permission?
Yes, but it is much less common and usually sounds very formal.
Might I ask a question?
Might I make a suggestion?
These constructions are grammatical, but they may sound unusually polite, formal, or old-fashioned in everyday conversation.
For ordinary permission, may is much more useful.
And when permission is granted, English normally uses may or can:
Yes, you may.
Yes, you can.
Using Might for Tentative Suggestions
Might is common when a suggestion is presented gently.
You might want to check the figures again.
We might consider moving the meeting to Friday.
Olivia might try calling the office directly.
The speaker leaves room for the other person to decide what to do.
This suggestion use is much more characteristic of might than may.
May Have vs. Might Have for Past Possibility
Both verbs can combine with:
have + past participle
to express uncertainty about an earlier situation.
Ethan may have missed the train.
Sofia might have left her phone at home.
Other examples:
The message may have gone to the wrong address.
Daniel might have forgotten about the appointment.
Both forms can describe a past event when the speaker does not know exactly what happened.
So it is inaccurate to say that may belongs to the present while might is simply its past form.
Might Have for an Unrealized Past Possibility
Might have has another important use. It can describe something that was possible under different circumstances but did not happen.
If we had left earlier, we might have caught the train.
They did not catch it.
Without the guardrail, the car might have gone over the edge.
The car did not go over the edge, but that outcome was possible.
This is different from simple uncertainty about the past:
Maya may have taken the earlier bus.
Here, the speaker does not know whether Maya took it.
In clearly counterfactual past situations, might have is especially natural.
Might in Hypothetical Situations
Might is common when a possible result depends on an imagined, uncertain, or remote condition.
If I had more time, I might learn Japanese.
If the rent were lower, they might move downtown.
In open future conditions, both may and might can occur:
If the weather improves, we may stay another day.
If the weather improves, we might stay another day.
The second can sound more tentative, but the conditional itself does not automatically require might.
More remote hypothetical situations strongly favor might:
If I lived closer, I might visit more often.
Might in Reported Speech
Might can appear when a statement containing may is reported from a past viewpoint.
Direct speech:
Ava said, “I may arrive late.”
Reported speech:
Ava said that she might arrive late.
Another example:
“The road may be closed,” Noah warned.
Noah warned that the road might be closed.
This relationship is one reason might is sometimes described as a past or backshifted form of may.
But many uses of might have nothing to do with past time:
I might call you tonight.
This clearly refers to the future.
Does May Always Change to Might in Reported Speech?
No.
Backshifting may to might is common when a statement is reported from a past viewpoint, but it is not an automatic mechanical rule in every context.
A speaker may retain may when the possibility is still current or when there is no reason to shift the modal.
The important distinction is that might has an established reported-speech relationship with may, while also functioning independently in present and future contexts.
May Not vs. Might Not
The negative forms are:
may not
might not
Both can express the possibility that something will not happen or is not true.
Nina may not attend the conference.
Leo might not finish before five.
In both sentences, the negative situation is possible but uncertain.
May Not Can Also Express Prohibition
Because may can express permission, may not can also mean that something is not permitted.
Compare:
Priya may not come tonight.
This can mean that perhaps Priya will not come.
But:
Visitors may not enter this area.
In this context, it normally means:
Visitors are not permitted to enter.
The surrounding context tells you whether may not expresses uncertain possibility or denied permission.
Questions with May and Might
May is especially common in permission questions:
May I speak to the manager?
May we begin now?
Might can appear in possibility questions:
Might this be the missing piece?
Might there be another explanation?
These questions are grammatical, though they can sound more formal or tentative than everyday alternatives.
For ordinary possibility, English often prefers structures such as:
Do you think it may rain later?
rather than:
May it rain later?
The second can sound unnatural for an ordinary question about whether rain is possible.
May Be vs. Maybe
May be and maybe are different grammatical forms.
May be contains the modal may followed by be:
The answer may be correct.
Maybe is an adverb meaning perhaps:
Maybe the answer is correct.
Both sentences express possibility, but their grammatical structures are different.
Compare also:
The answer might be correct.
Here, might is another modal followed by be.
May Well and Might Well
Both modals can occur with well.
The delay may well continue into tomorrow.
She might well refuse the offer.
In these expressions, well suggests that the possibility is quite reasonable, plausible, or understandable.
It should still not be converted into a precise probability percentage.
May vs. Might: Quick Comparison
| Use | May | Might |
|---|---|---|
| present possibility | yes | yes |
| future possibility | yes | yes |
| always shows greater certainty | no | no |
| asking formal permission | common | possible but very formal |
| granting permission | yes | not normally |
| tentative suggestion | uncommon | common |
| reported form related to may | no | common |
| remote hypothetical situations | less typical | common |
| uncertain past with have + past participle | yes | yes |
| unrealized past possibility | possible in limited contexts | especially common |
The main lesson is that may and might overlap greatly in ordinary possibility but become more distinct in other grammatical contexts.
How to Choose Between May and Might
For an ordinary present or future possibility, either form may be possible.
The store may close early.
The store might close early.
Then consider whether the sentence has a more specific function.
Use may for standard formal permission:
May I leave?
Use might for a gentle suggestion:
You might want to call first.
Use might naturally in more remote hypothetical situations:
If I lived nearby, I might walk to work.
Use may have or might have when the speaker is uncertain about an earlier event:
She may have taken the wrong train.
He might have misunderstood the instructions.
Use might have especially naturally for an unrealized past possibility:
If we had hurried, we might have caught the bus.
There is no need to decide between may and might by assigning each one a percentage of certainty.
May vs. Might Examples
The parcel may arrive tomorrow.
May expresses future possibility.
Daniel might be at the library.
Might expresses present possibility.
May I borrow this chair?
May asks for permission.
You may start whenever you are ready.
May grants permission.
You might want to save a copy before editing the file.
Might makes a tentative suggestion.
The courier may have left the parcel with a neighbor.
May have left expresses uncertainty about an earlier event.
Grace might have taken the wrong exit.
Might have taken also expresses uncertain past possibility.
If the rope had broken, someone might have been injured.
Might have been injured describes an unrealized past possibility.
Marcus said he might join us later.
Might can occur when an earlier may is backshifted in reported speech.
Students may not use phones during the examination.
Here, may not means that permission is denied.
May and might overlap widely when they express possibility. Might can sound more tentative in some contexts, but the difference cannot be reduced to a fixed scale of certainty.
The clearer distinctions appear elsewhere. May has an important role in permission, while might is especially common in tentative suggestions, remote hypothetical situations, reported speech, and unrealized past possibilities. Both may have and might have can express uncertainty about earlier events.
Looking at the complete sentence gives you a much more reliable answer than simply asking which modal sounds “more likely.”
The First English Grade Editorial creates simple English grammar, vocabulary, and language guides for students, beginners, and everyday learners.