What Are Modal Verbs? Usage Guide and Examples

Modal verbs work with other verbs to show possibility, necessity, ability, permission, and suggestion (known as modalities).

Modal verbs, also known as modal auxiliary verbs or helping verbs, don’t have conjugated forms, so they don’t change form based on the verb tense of the sentence.

For example: 

• Can we please go to the concert?
• The teacher might be back on Tuesday.
• Laura could stop by later.
• I will be home for dinner.

Modal verbs can only function on their own if the main verb is obvious. For example, the sentence “I will” doesn’t make sense on its own. But when it follows the sentence “Who will be home for dinner?” then the reader understands that the sentence is really “I will be home for dinner.”

The modal verbs in English are:

• can
• could
• may
• might
• must
• shall
• should
• will
• would

You see modal verbs everywhere you look — probably without even realizing it. Some can be used in many ways, while others only work in one or two contexts.

The modal verbs could, may, and might indicate that there is a possibility or probability that something will happen.

• I could pass this class.
• Jason may bring chips to the party.
• My parents might say yes.
• You could get hurt.
• Lola may change her mind.

When you exchange these verbs for other modal verbs, such as will and shall, they indicate a promise or certainty that something will happen.

• I shall pass this class.
• Jason will bring chips to the party.
• My parents will say yes.
• You will get hurt.
• Lola will change her mind.

You’ll often find modals used this way in the conditional mood, which states that something might happen if another event happens as well. For example, “I could pass this class if I study” changes the possibility (passing the class) based on what needs to happen first (studying).

You can use the modal verb must or should to indicate that something needs to happen. It functions like the expression have to to show an obligation or necessity. When you add not, it indicates that something should not happen.

• I must learn to drive.
• We should work together.
• The teacher should extend the deadline.
• Katie must work harder.
• My sister must feed her dog.

Notice that the degree of need depends on the modal you choose. “I must learn how to drive” has a higher need than “I should learn how to drive.”

Can is the main modal verb that shows one’s ability to do something. If you can replace can with able to, it’s being used as a modal of ability.

• I can swim well.
• Our class can solve the math problem.
• We can beat the other team.
• Percy can hold his breath for two minutes.
• Mr. Tracer can meet with you until tomorrow.

Could is a modal verb that shows one’s past ability. For example, “I could swim well as a child” indicates that the speaker could swim well in the past.

Modal verbs can be used to ask permission or grant permission. These verbs include could, may, shall, and would. Granting permission usually uses the modal may.

• Could I borrow your pencil? (Yes, you may.)
• May I be excused? (No, you may not.)
• Shall I take your coat? (Yes, you may.)
• Would you mind if I sat here? (No, I wouldn’t.)

Some speakers add can to this list, as in “Can I spend the night at David’s house?” Strict grammarians believe that may is the proper modal verb to use in these cases, as can is traditionally a modal of ability. However, the rules regarding can vs. may have loosened up to allow can as a modal of permission in informal cases.

Another use of modal verbs is to make suggestions. Use could, might, must, and should to make a suggestion or give advice, often with the verbs want to or consider.

• We could split a pizza.
• You might want to wait until tomorrow.
• Tim must consider a third option.
• You should wear a coat today.

You can also use modal verbs of necessity in imperative sentences. Must and should are commonly found when a speaker gives advice or makes commands.

How can you change the mood of a sentence in which an action doesn’t happen? These sentences, known as negative sentences, include modal verbs and the word not (or a contraction with the word not).

• We should not open these presents early.
• John might not arrive until 3:00 today.
• The team wouldn’t play without their goalie.
• I can’t go to the zoo today.

Modal verbs don’t just appear in present tense sentences. Many times, you’ll find them in past tense sentences and future tense sentences to talk about actions in different time periods.

Past modal verbs, such as could, might, should, and would use the verb have with a past participle to discuss something that was once possible, needed, able to be done, or permitted but no longer is.

• I could have become a big star.
• My boss might have been a little rude.
• The teacher should have explained the homework better.
• We would have helped you.

Past modal verbs such as may and might can also speculate about something that has happened. As in other modal examples, adding not makes the sentence negative.

• John may have missed his plane.
• Judith might have gotten lost.
• We may not have seen the sign.
• This might not have been the best idea.

Some modals, such as can and shall, don’t work as past modals. Use could have and should have in these cases.

All future verb tenses show possibility since they describe actions that haven’t happened yet with the verb will (“I will come to your party”). But other modal verbs sound incorrect when you put them in future tense (“I will can come to your party tomorrow” is all kinds of wrong).

So what do you do instead? Use the phrase be able to when showing possible ability in the future.

• I will be able to come to your party tomorrow.
• She will be able to call you tomorrow.
• John will be able to drive the truck next year.
• We will be able to start construction once the materials arrive.

Does it seem like there are some words missing from the list above? Several English verbs and expressions function just like modals. They are sometimes called semi-modals, and they tend to be more conversational than modal verbs.

• be able to (We’ll be able to rest soon.)
• dare (I dare not enter without permission.)
• had better (You’d better ask for the day off.)
• have to (I have to get an A on this test.)
• ought to (Shannon ought to buy a new car.)
• need to (We need to think of a plan.)

Modal verbs show intention rather than action. When used with other verbs in the sentence, they can make your meaning as clear as you want it to be. Test your knowledge of modal verbs with an examination of may vs. might or maybe vs. may be. You can also make sure you’re using can vs. could correctly in your writing and everyday speech.