How many modal verbs are there in English?

There are nine core modal verbs: can, could, may, might, must, shall, should, will and would. English also has semi-modals such as ought to, had better, have to and need to, which carry similar meanings but do not follow all of the same grammar rules.

What is the difference between 'must' and 'have to'?

'Must' generally expresses an obligation the speaker feels themselves, while 'have to' expresses an obligation that comes from outside, such as a rule or a law. In everyday spoken British English, 'have to' is the more common of the two.

Is 'shall' still used in British English?

Yes, but in a narrower way than it once was. It is most common in offers and suggestions with 'I' and 'we' — 'Shall I carry that?', 'Shall we go?' — and in formal or legal writing. For ordinary future statements, British speakers now use 'will'.

What level do I need to be to use modal verbs correctly?

Basic modals such as can, must and should are taught at A2 level. The more subtle uses — degrees of possibility, and past forms like 'must have' and 'should have' — are usually developed between B1 and C1, which is where most of our adult classes focus.

How can I practise modal verbs?

Speaking is the fastest way, because modals are about attitude, and attitude only becomes natural when you use it in real conversation. Describe your week using 'I had to', give a friend advice using 'you should', and guess about a photograph using 'she might be'. In class our teachers correct these in the moment, which is what fixes them.

Free grammar guide

Modal verbs in English

Modal verbs are the small words that change the whole meaning of a sentence. 'I go' is a fact. 'I must go' is an obligation, 'I might go' is a possibility and 'I should go' is advice. This guide explains each one, with examples you can use today.

Level: A2 to C18 minute readFree to use

What a modal verb is

A modal verb sits in front of another verb and tells the listener how you feel about that action: whether it is possible, necessary, permitted, likely or advisable.

The nine core modal verbs in English are can, could, may, might, must, shall, should, will and would. You will also meet semi-modals such as ought to, had better, have to and need to, which behave in a similar way but follow slightly different rules.

I can swim.

Ability — I have the skill.

I must leave at six.

Obligation — I have no real choice.

It might rain later.

Possibility — I am not certain.

You should rest.

Advice — this is my recommendation.

The three rules that never change

Modal verbs are unusually well behaved. Once you know these three rules, most of your mistakes disappear.

The verb after a modal has no 'to': 'She can drive', never 'She can to drive'. The one exception is 'ought to'.
Modals never take an -s in the third person: 'He can', 'She must', 'It should'. Never 'He cans'.
Modals form questions and negatives without 'do': 'Can you help?' and 'I cannot come', never 'Do you can help?'.

Can, could and be able to

'Can' expresses present ability, informal permission and general possibility. 'Could' is its past form, but it is also the softer, more polite version in the present.

Use 'be able to' when you need a form that 'can' does not have, such as a future or a perfect form: 'I will be able to help tomorrow', 'I have never been able to whistle'.

For a single successful action in the past, English prefers 'was able to' or 'managed to' over 'could': 'I was able to book a table' sounds natural, whereas 'I could book a table' suggests a general ability rather than one occasion.

Could you open the window, please?

More polite than 'Can you'. Both are correct.

When I was six I could already read.

General ability in the past.

The traffic was terrible, but we were able to arrive on time.

One specific past success.

Must, have to and mustn't

'Must' usually comes from the speaker: it is your own sense of obligation. 'Have to' usually comes from outside: a rule, a law or a timetable. In everyday British English, 'have to' is far more common.

The negatives are completely different in meaning, and this catches out students at every level. 'Mustn't' means it is forbidden. 'Don't have to' means it is not necessary.

I must ring my mother this evening.

My own decision — nobody is forcing me.

Students have to register on the first Monday.

A school rule, not a personal wish.

You mustn't smoke in the building.

It is prohibited.

You don't have to come early.

You may if you wish, but it is not required.

May, might and could for possibility

When you are guessing about the present or the future, 'may', 'might' and 'could' are close in meaning. 'May' is slightly more formal and slightly more certain; 'might' suggests a smaller chance.

'May' also has a second, more formal use: asking for or giving permission. 'May I come in?' is the polite version you would use with a stranger or in an interview.

She may be in the library.

A reasonable guess.

He might not come to the party.

Possible, but less likely.

May I borrow your pen?

Formal permission.

Should, ought to and had better

All three give advice, with rising strength. 'Should' is ordinary advice. 'Ought to' is very close in meaning but sounds a little more formal and is used less often in speech. 'Had better' carries a warning: something bad will happen if you do not.

'Should' also expresses expectation: 'The train should arrive at nine' means that is what is scheduled, not that the train has a duty.

You should book early — the summer courses fill up.

Advice.

We ought to tell her the truth.

Advice, slightly more formal.

You'd better take an umbrella.

A warning. Note 'had better' + bare infinitive.

Talking about the past: modal + have + past participle

To use a modal about the past, put 'have' plus a past participle after it. The modal itself does not change.

This is one of the clearest signs of an advanced speaker, and it is worth practising out loud, because the spoken form is almost always contracted: 'must've', 'should've', 'could've'.

She must have missed the bus.

I am fairly certain that is what happened.

You should have told me.

Criticism — you did not tell me, and that was a mistake.

He can't have finished already.

I am certain he has not finished.

I might have left it at home.

It is possible, I am not sure.

Mistakes our teachers hear most often

She can to speak four languages.

She can speak four languages.

No 'to' after a modal verb. The only common exception is 'ought to'.

He musts finish the exercise.

He must finish the exercise.

Modal verbs never add -s in the third person singular.

You mustn't pay — entry is free.

You don't have to pay — entry is free.

'Mustn't' means forbidden. When something is simply unnecessary, use 'don't have to'.

I should of called you.

I should have called you.

'Should of' is a spelling of the spoken contraction 'should've'. It is always wrong in writing, and native speakers make this mistake too.

Do you can help me?

Can you help me?

Modal verbs make their own questions. Never add 'do'.

I will can drive next year.

I will be able to drive next year.

You cannot put two modal verbs together. Use 'be able to' for the future.

Questions students ask

How many modal verbs are there in English?: There are nine core modal verbs: can, could, may, might, must, shall, should, will and would. English also has semi-modals such as ought to, had better, have to and need to, which carry similar meanings but do not follow all of the same grammar rules.
What is the difference between 'must' and 'have to'?: 'Must' generally expresses an obligation the speaker feels themselves, while 'have to' expresses an obligation that comes from outside, such as a rule or a law. In everyday spoken British English, 'have to' is the more common of the two.
Is 'shall' still used in British English?: Yes, but in a narrower way than it once was. It is most common in offers and suggestions with 'I' and 'we' — 'Shall I carry that?', 'Shall we go?' — and in formal or legal writing. For ordinary future statements, British speakers now use 'will'.
What level do I need to be to use modal verbs correctly?: Basic modals such as can, must and should are taught at A2 level. The more subtle uses — degrees of possibility, and past forms like 'must have' and 'should have' — are usually developed between B1 and C1, which is where most of our adult classes focus.
How can I practise modal verbs?: Speaking is the fastest way, because modals are about attitude, and attitude only becomes natural when you use it in real conversation. Describe your week using 'I had to', give a friend advice using 'you should', and guess about a photograph using 'she might be'. In class our teachers correct these in the moment, which is what fixes them.

Practise this with a teacher

Reading about grammar helps. Using it every day with a teacher who corrects you helps far more. We are a small, not-for-profit English school in Brighton with a maximum of 14 adults in a class.

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