The two words may and might cause a lot of confusion in English and many writers aren’t sure when to use which one. A lot of people use them interchangeably, especially in speech, but is there really no difference between the two?

Today I want to clear up any confusion between these two words and outline the unique characteristics of each of them. I will cover their functions within the sentence, the grammar behind each word, and give plenty of examples so you won’t ever mix them up again.

May and Might When Expressing Possibility

In popular usage and speech, may and might are used interchangeably when referring to possibility and probability, but there is a slight difference between the two.

May is used to express what is possible, factual, or could be factual. For example,

• He may lose his job.
• We may go on vacation.
• I may have dessert after dinner.

Might is used to express what is hypothetical, counterfactual, or remotely possible. For example,

• If you hurry, you might get there on time.
• If I had shown up on time, I might have kept my job.
• If I win the lottery, I might buy a Ferrari.

Right away we notice that might deals with situations that are speculative or did not actually happen, i.e. hypothetical, whereas may deals with situations that are possible or could be factual.

An easy way to express/remember this difference is that might suggests a lower probability than does may. If something is very far-fetched, you probably want to use might. You could say might is for things that are mighty far-fetched.

Might is the Past Tense of May

The second distinction, which is the more important of the two, between these two words is that might is the past tense of may. In most confusing situations, you can easily make the correct choice by remembering this fact. For example,

• He might have called earlier, but I was not home. (Past tense)
• The criminal might not have been caught, had you not sounded the alarm. (Past tense)
• I may go to the movies tonight. (Present tense)

If you can determine the tense of your sentence, you can easily choose between might or may.

Can You Use Might / May Have Interchangeably?

Some people claim that you can use might have and may have interchangeably, but this is a bad idea. May have should not be used in the past tense.

According to the American Heritage Dictionary’s 2012 Usage Panel survey, the vast majority of experts disagree with using might have and may have in the same contexts. AHD provided their panel with the following two sentences,

• If John Lennon had not been shot, the Beatles might have gotten back together.
• If John Lennon had not been shot, the Beatles may have gotten back together.

In the survey, 97 percent of the Usage Panelist found the first sentence to be acceptable while only 32 percent found the second sentence to be acceptable.

Far from just a few grammar-loving pedants, the majority of experts view this distinction as necessary, and if you’re writing for any kind of professional audience, you will want to make sure you’re keeping these two words separated.

May and Might When Asking Permission

May and might can also both be used when asking for permission. For example,

• You may have another piece of cake.
• May I go to the restroom?
• Might I ask when the movie starts?
• Might I ask for a favor?

When asking for permission, may is much more common than might.

While both of these words can be used to ask permission, if you’re not careful, they can lead to ambiguity. For example, if you were to ask the question,

• May I go to the movies tonight?

You will want to be clear when you go to tell your friends whether or not your received permission. For example,

• I may not go to the movies tonight.

When you say this, do you mean “I am not allowed to go to the movies tonight” or do you mean “I might not go to the movies tonight?”

In situations like this, it’s best to use might to avoid any confusion that might arise.

• I might not go to the movies tonight.

Summary:

It’s important to keep might vs. may separated so you can maintain clarity in your writing.

• Might carries with it less probability and applies to hypothetical and counterfactual situations. Might is also the past tense of may.
• May applies to situations that are possible or could be possible.

When talking about something that is not happening, it can be better to use might to avoid confusion with the permissive may.