Modal verbs

This page has introductory information about the modal verbs in English.

The modal verbs include can, must, may, might, will, would, should. They are used with other verbs to express ability, obligation, possibility, and so on. Below is a list showing the most useful modals and their common meanings:

Modal
Meaning
Example
can
to express ability
I can speak a little Russian.
can
to request permission
Can I open the window?
may
to express possibility
I may be home late.
may
to request permission
May I sit down, please?
must
to express obligation
I must go now.
must
to express strong belief
She must be over 90 years old.
should
to give advice
You should stop smoking.
would
to request or offer
Would you like a cup of tea?
would
in if-sentences
If I were you, I would say sorry.

Modal verbs are unlike other verbs. They do not change their form (spelling) and they have no infinitive or participle (past/present). The modals must and can need substitute verbs to express obligation (have to) or ability (able to) in the different tenses. Here are some examples:

Must

Past simple
Sorry I'm late. I had to finish my mathematics test.
Present perfect
She's had to return to Korea at short notice.
Future
You'll have to work hard if you want to pass the exams.
Infinitive
I don't want to have to go.

Can

Past simple
I couldn't/wasn't able to walk until I was 3 years old.
Present perfect
I haven't been able to solve this problem. Can you help?
Future
I'm not sure if I will be able to come to your party.
Infinitive
I would love to be able to play the piano.

Modals are auxiliary verbs. They do not need an additional auxiliary in negatives or questions. For example: Must I come? ( Do I must come? ), or: He shouldn't smoke ( He doesn't should smoke ).

Important: The explanations and examples on this page are just an introduction to this extensive and complex area of English grammar. Elsewhere on this site you can read more about each of the modal verbs and their difficulties.

Students of English who want to explore the topic further are recommended to consult a good reference work, such as Swan's Practical English Usage.

There are several interactive quizzes on the modals in the Verb grammar: Miscellaneous drop-down menu on the Grammar index.