What are modal verbs in English?

Modal verbs in English are words like can, must, should, may etc. They are a group of auxiliaryNo definition set for auxiliaryLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. verbs that are always used together with the main verbNo definition set for main verbLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. in its rootNo definition set for rootLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. form. But unlike other auxiliary verbs, modal verbs never change their forms.

Modal verbs provide information about the modality of a verb: or the reason or purpose for discussing a verb. Therefore a modal verb can be used to show that an action is…

We use modal verbs a lot in English. You will need them if you want to sound polite, when you talk about rules, or when you’d like to express how sure you are about something.

In this post, we’ll cover…

• what verbs are considered modal verbs in English

• how modal verbs are different from other verbs

• what meanings modals can express

• how to use English modal verbs

Let’s dive right in!

There is no agreement on exactly which verbs are modal verbs in English. However, most textbooks will list these nine at least:

There are also a number of verbs and phrases that are a lot like modals, but are a little different in structure or use. These verbs can be called modals, semi-modals, phrasal modals, or quasi-modals. Some of these are:

The focus of this post will mostly be on “proper modals,” but “semi-modals” are going to be discussed as well where appropriate.

English modal verbs have some special features that make them different from other verbsNo definition set for verbsLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. (and challenging to use!)

• No agreement:

  Modal verbs do not change their form to agreeNo definition set for agreeLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. with the subjectNo definition set for subjectLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. of a sentence, for example:

  • I ride a bike to work.

    I should ride a bike to work.

  • He rides a bike to work.

    He should ride a bike to work.

  • I am riding a bike to work.

    I should be riding a bike to work.

  • He is riding a bike to work.

    He should be riding a bike to work.

  Modals also don’t change their forms with the tense of a sentence either:

  • I was riding a bike yesterday.

    I should have been riding a bike yesterday.

  • I am riding a bike right now.

    I should be riding a bike right now.

  Important

  Modals often change their meaning or follow different grammar rules in different tenses, but just looking at the form of the modal verb itself is not enough to tell you about the tense of the sentence.

• No non-finite forms:

  Modals don’t have non-finiteNo definition set for non-finiteLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. forms (namely, infinitives, participles, or gerunds). “Semi-modals” or other synonymous expressions can be used instead in situations when a non-finite form is required. Compare:

  • I want to ride a bike to work.
    ❌ I want to can ride a bike to work.

    → Instead say: I want to be able to ride a bike to work.

  • I like riding a bike to work.
    ❌I like canning ride a bike to work.

    → Instead say: I like being able to ride a bike to work.

  • Riding a bike to work, I save a lot of money.
    ❌ Canning ride a bike to work, I save a lot of money.

    → Instead say: Being able to ride a bike to work, I save a lot of money.

• The modal verb is always the first auxiliary verb:

  When you use a modal verb, it always comes before any other auxiliary verbs and there is only ever one modal verb in a clause.

  This means that the modal verb is the one most involved in forming questions and negative sentences:

  • You should ride a bike to work.

  • Should you ride a bike to work?

  • You should not ride a bike to work.

• Modal verbs do not change their form with the tense:

  Modal verbs only have one form. However, you can change the way you use them in a sentence to show whether you are talking about the present/future or about the past.

  When modals are followed by the root form of the verb, they usually have present or future time reference:

  • My brother can skate really well.

    → now and in the future

  • I think we should book a place to stay.

    → now and in the future

  • She may/might/could be in the backyard.

    → now or in the future

  • I must sell the house by September.

    → now or in the future

  • Use could, might, or would with the root form of the verb as equivalents of past tense forms for can, may, and will respectively, but such uses are limited to certain meanings of these modal verbs. Compare:

    Present:

    My brother can skate really well. He will skate every day after school in the winter. We think he may join a hockey team, but he doesn’t like team sports.

    Past:

    My brother could skate really well when he was a child. He would skate every day after school in winter. We thought he might join a hockey team, but he didn’t like team sports.

  • Use have + past participle after modal verbs to create a reference to the past:

    • There were no vacancies in the hotels in town. We should have booked a place to stay in advance.

    • She didn’t answer the door. She may/might/could have been in the backyard.

    → Have + past participle is also known as a “bare perfect infinitive”!

  • Use “semi-modals” or other phrases to replace modal verbs that cannot be used with the past time reference:

    • I must sell the house by September.

      → present

    • I had to sell the house by September.

      → past

• The meaning in which a modal is used shapes its grammar:

  Most modal verbs have more than one meaning, and the way they are used in positive and negative sentences, or with reference to present/future or past, depends on the meaning. Let’s take a look at the modal verb must to illustrate this:

  * These are the cases of replacing a modal verb with its semi-modal synonym.

  	Meaning of obligation (= necessary, important)		Meaning of deduction (= highly likely)
  Present/future, positive sentence	We must tell her what happened.		David is not in his office now. He must be on the way home.
  Present/future, negative sentence	We mustn’t tell her what happened. → It is important not to tell her.	We don’t have to* tell her what happened. → We do not need to tell her, but we can if we want to.	David is in his office now. He can’t be on the way home.
  Past, positive sentence	We had to* have our passports ready before we could travel to Europe.		David was not in his office at 5 p.m. yesterday. He must have been on the way home.
  Past, negative sentence	We didn’t have to* have our passports to travel to Puerto Rico.		David was in his office at 5 p.m. yesterday. He couldn't have been on the way home.

As you can see, the negative form of must, might be, mustn’t, not have to, or can’t, depending on the meaning. There are differences in its past forms too.

Because of all these limitations we described above, modal verbs are sometimes called “defective,” which is quite unfair given how much they can do even with the limited range of forms they have! Let’s find out how you can use modal verbs.

In this section, we’ll introduce the most important English modal verbs, and talk a bit about how to use them in positive and negative sentences, with reference to present/future or past.

To talk about likelihood

Modal verbs are commonly used to express the possibility or probability of an event or action. They show how likely or unlikely it is from the speaker’s point of view that something will happen in the future, is happening now, or happened in the past.

Let’s take a look at the picture and see how modals can help you describe likelihood.

Likelihood	Modal verb	Present/future	Past
90-99% The speaker is practically certain that something is true.	must	This must be a Halloween party.	The kids must have chosen their costumes in advance.
80-89% The speaker expects something to be true.	should	The kids should go trick or treating soon.	More kids should have come to the party, but they didn’t. → about something that was expected, but didn’t happen, or when the speaker doesn’t know if it happened or not
Around 50% The speaker believes something is possible to be true.	may could might → May is more formal.	The kids may / could / might come back with their buckets full of candy.	The kids may / could / might have used the same buckets last year.
0% The speaker believes something is not true.	can't	This can’t be the 4th of July.	The kids can’t/couldn’t have made these costumes themselves.

Note that in the meaning of likelihood we do not use negative forms of must or should. It is possible, however, to say may not / might not without much change to the meaning of a sentence, as the chances are still 50/50.

To learn more about how to talk about likelihood in English, check out our post on making deductions with modals in English!

To talk about ability

We mostly use the modal verbs can and could to say that someone has the ability to do something.

In English, it is important to distinguish between the ability someone has in general and the ability to do something at a specific moment.

We can use be able toinstead of can in all situations describing abilities, but it’s especially useful when an infinitive or a participle that modals don’t have is required:

• My brother has been able to teach me the basics of playing chess.

• I’d like to be able to play chess as well as he does!

In the present or future, the verb can will work for both types of ability, but could only works with an ability in a specific moment. Compare these two sentences:

• My brother can play chess really well.

  → This sentence talks about someone’s ability in general.

• My brother can/could beat you today.

  → This sentence describes someone's ability at a certain moment.

When you talk about an ability in the past, the rules are a little more complex:

• To describe a general ability in the past, use could + root:

  My brother could play chess really well when he was a child.

  → This describes a general ability in the past.

  The sentence above only describes a general ability existing in the past, so in this meaning we may say that could is a past form of can.

• To describe an ability to do something in specific past circumstances, the modal verb depends on whether or not you actually did it:

  • If you actually did it, use was able to or managed to:

    • My brother was able to beat you yesterday.

      → He had the ability to win, and he did win.

    • My brother managed to beat you yesterday.

      → He had the ability to win, and he did win.

  • If you did not actually do it, use could + have + past participle

    My brother could have beaten you yesterday.

    → He had the ability to win, but you did not play chess, so he did not win.

• To say that there is a lack of ability, we use cannot/can’t for present and future, and couldn’t for past:

  • My brother cannot play chess.

  • My brother couldn’t play chess as a child.

  • My brother can’t beat you today.

  • My brother couldn’t beat you yesterday.

To ask for and to give permission

We use can or may (a bit more formal) when we want to give someone permission to do something:

You can/may pet my dog.

To ask for permission, we commonly use can and may. You can also use could and might in questions, but this is less common and sounds hesitant.

• Can / May I pet your dog?

  → common way to ask

• Could / Might I pet your dog?

  → hesitant and indirect, but polite

If you don’t want to give permission, use cannot / may not:

You cannot / may not pet my dog.

If permission was given in the past, you’d normally have to resort to other phrases to talk about it, for example:

The boy allowed me / gave me permission to pet his dog.

However, you can also use could to report that you someone had permission in the past:

I knew that I could pet his dog.

To make requests

We use the modal verbs can, could, would, and might when we want to ask someone to do something. Could, would, and the rarely-used might make the request especially polite:

• Can / Could you show me how to edit this picture?

• Would you share this file with me, please?

• Might I take a look at that diagram again?

• Could I borrow your laptop for a second, please?

• Would you mind sending this file to me?

To talk about necessity

We use different modal verbs (must, need, have (got) to) to talk about orders, rules, instructions, and other things that we are required to do or feel like it’s our duty to do.

Must is a formal way to show necessity. We use must in situations when the speaker has a firm opinion or the authority to insist on a certain course of action:

• You must choose only one answer for each question.

  → an instruction from authority

• I simply must pass the test this time!

  → something we believe is necessary

• You must take a test to get your driver’s license.

  → something that rules mandate

• You must practice a lot before the test.

  → advice given with lots of experience

In everyday speech, have (got) to in everyday speech, especially when it is the situation that makes someone do something, not the speaker.

• You have to have at least 20 correct answers to pass.

  → These are the requirements.

• I’ve got to wake up early tomorrow to take the driver’s test.

  → I don’t want to, the circumstances force me to.

TipSound like a native!

When the phrase have got to is said quickly it can sound like “gotta” or “hafta”:

• I have got to go. → I’ve got to go. → “I’ve gotta go.” → “I gotta go.”

• I have to go. → “I hafta go.”

We also use have (got) toinstead of must when a proper modal verb cannot be used due to its lack of certain forms. For example, we do not use must to talk about necessity in the past, or when we need an infinitive, so we use have (got) to instead:

• I had to take a test to get my driver’s license.

• If you are late for the test, you will have to take it on another day.

Important

The negative forms must not and not have to have very different meanings!

• We use must not or mustn’t to say that something is prohibited (not allowed):

  You mustn’t use your mobile phones during the test.

  → It is forbidden!

• We use not have to / not need to when something is not necessary, but possible:

  You don’t have to answer the questions in the order they are given.

  → However, if you want, you may!

To give advice

We use should or, less often, ought to, to give someone advice or recommendation to do something:

You should add more salt and pepper.

We may also recommend someone not to do something:

You shouldn’t add any salt or pepper.

We may also recommend someone not to do something:

• Speaker A:

  Shall/Should I add some salt and pepper?

• Speaker B:

  Yes, please do.

You can also express disapproval or regret about a past action (sort of advice about the past) using should have:

It’s hard to mix salad in this bowl, it’s too full. You should have used a bigger bowl.

To learn more ways to express disapproval about a past action, check out our post on expressing regret in English!

We may use had better instead of should when we want to recommend the best course of action in a specific situation. It is a bit stronger than should, it sounds like a teacher or parent, and implies that there might be some negative consequences if the advice is not followed:

• You’d better add salt and pepper now before you forget.

• You’d better not mix salad in this bowl, it’s too full.

Tip

Sometimes English speakers phrase advice as a necessity or a possibility, and so they use might, need to, have got to, or other modals when they really mean should:

• We are going hiking this weekend. You might like to join us.

• You look tired. You need to go to bed early today.

• It’s my first match as a college student. You have got to be there!

To talk about habits

We use will for present time and would for past time to describe a pattern in events or in someone’s behavior. If these modal verbs are stressed, the speaker is really annoyed by the persistence with which something happens:

• When we were small, my sister would always dress just like me!

  → past habit: use would

• If my sister has a chance, she will still always dress just like me!

  → present habit: use will

You can use used to instead of would, but the sentence will lose its emphasis.

How to describe a habit in the present?

Remember that to talk about a present habit, you can always use the present simple on its own! Check out our post on the present simple in English to review.

Tip

You are probably familiar with will as an auxiliary verb indicating future, and finding it among modal verbs might be surprising. Yet, it is technically a modal verb, because its use simply to say what the future holds (predictive meaning) is just one of its many uses, such as:

• To guess that something is true:

  Speaker A:

  Who is that tall man?

  Speaker B:

  That will be my husband, Tom.

• To promise:

  You will come with us next year.

• To request:

  Open the window, will you?

• To state a general truth:

  This cup will hold 300 ml.

Modal verbs are a very special category of verbs in English. They act as auxiliary verbs in forming interrogative and negative sentences, but they can also bear a range of additional meanings, such as ability, expectation, recommendation, necessity, prohibition, certainty, and others. They all share some characteristics:

• They do not have endings, such as -s, -ing, -ed.

• They act as auxiliaries in forming questions and negations.

• The way they show the past reference depends on the meaning in which they are used.

Still, each modal verb is unique in its meanings and uses and should be studied individually. Feel ready to try out what you’ve learned so far using these modal verb practice activities?