May or might: what’s the difference?

The verb may is used in five main ways:

• to talk about a possible situation: Those reports may prove to be false.
• to politely ask for permission to do something:  May we come in?
• to politely give someone permission to do something: That’s all for now, you may go.
• to admit that something is the case before stating a contrasting fact: The chorus may look silly, but they sound wonderful.
• to express a wish or hope:  May they be very happy in the future.

Basically, might is the past tense of may. It therefore seems logical for grammatical sticklers to argue that if you’re talking about a possible situation in the present or the future, you should always use the present tense, may:

If you’re feeling queasy, you may eat less and lose weight.

 And, equally, if you’re referring to something which could have been the case in the past, the past tense, might, is said (by the grammatically orthodox) to be correct:

For all we know, she might have been undergoing counselling.

However, people don’t often make this distinction in today’s English, and it’s generally acceptable to use either may and might to talk about the present/future or the past:

• Present or future event

√   She thinks she may be going crazy.

•  Past event

√  I might have forgotten to mention it at the time.

Distinctions between may and might

So the general rule is that may and might are usually interchangeable when talking about possible situations. However, there are a few differences in usage between may and might and it’s useful, especially if you’re writing for school, college, or work, to know when each

Degrees of possibility

Some authorities on English usage state that it’s better to use may when you think the chances of something being the case are likely and to use might when it is unlikely (though in practice, this distinction isn’t always clear-cut):

They may visit Ireland in the near future.
[The speaker believes that there’s a fairly good chance that they may go to Ireland]

The woman looked as if she might have been in her late 40s.
[The speaker wasn’t very sure about the woman’s age, but made a tentative guess]

However, it’s preferable to use might rather than may if you’re talking about a hypothetical or conditional scenario:

 If I were Dutch I might see immigration differently.
 [I’m not Dutch, I’m an American talking about a theoretical situation]

If you go to bed earlier, you might feel better tomorrow.
[I think that perhaps you would feel better if you went to bed earlier]

To show annoyance 

If you want to express annoyance or criticism because someone could or should have done something that they* didn’t do, you should always use might rather than may:

√  You might have told me that she wouldn’t be in today!

X   You may have told me that she wouldn’t be in today!

√  You’d think they might be able to understand each other’s point of view a bit more.

X   You’d think they may be able to understand each other’s point of view a bit more.

5. Polite requests and suggestions

When politely or formally making a request, asking for information, or making a suggestion, might is regarded as preferable to may:

Don’t you think you might be a little old for him?

Might I ask the Court to glance briefly at the judgment of Sir Harry Gibbs?

6.  Expressing a wish or hope

If you want to express a wish or hope, then may is always the correct word to use:

√ May you both be very happy.

X  Might you both be very happy.

 7. Asking for and giving permission

When politely asking for permission to do something, it’s acceptable to use may or might, but nowadays might is regarded as very formal. May is considered more polite than the most typical way of asking permission in English, using can:

May I borrow your pen?  [polite]

Might I borrow your pen?  [polite and very formal]

Can I borrow your pen?  [less polite; considered by some to be incorrect usage**]

When giving (or refusing) permission, only may and can are acceptable:

√  Yes, you may (borrow my pen).  [polite]

√  Yes, you can (borrow my pen). [less polite]

X  Yes, you might (borrow my pen).

√  No, you may not (borrow my pen).  [polite]

√  No, you can’t (borrow my pen). [less polite]

X  No, you might not (borrow my pen).