English grammar · Intermediate
English Modals
The modal verbs (can, could, may, might, must, shall, should, will, would) add a speaker's judgement to a verb: how possible, how necessary, how certain, or how polite. They share one grammar, no -s, no to, no do in questions, and a bare infinitive after them, which is what makes them a family.
What it is
A modal verb sits in front of a main verb and colours it with the speaker's attitude. She swims is a fact; she can swim is ability, she must swim is obligation, she might swim is possibility, she should swim is advice. Nine core modals cover all of that, plus the semi-modals have to, need to, ought to, and be able to that fill their gaps.
You must be tired (deduction). You must leave now (obligation). Same modal, two meanings: context decides.
How to spot it
A modal never changes form and never takes to after it. If you see he cans or she must to, a modal has been treated like an ordinary verb.
- He can drive. (no -s on the modal, bare infinitive after it)
- Can he drive? (the modal itself moves to make the question)
- He can't drive. (not attaches directly to the modal)
- He has to drive. (have to is a semi-modal: it does take -s and do)
Modals have no past participle or -ing form. To say the same thing in another tense, switch to the semi-modal: I had to leave, I have been able to swim since I was five.
Modals Quick Reference
What each modal most often means
| Modal | Main meanings | Example |
|---|---|---|
| can | ability, permission, request | Can you swim? Can I leave early? |
| could | past ability, polite request, possibility | I could swim at five. Could you help? It could rain. |
| may | permission (formal), possibility | May I come in? It may snow tonight. |
| might | weaker possibility, tentative suggestion | She might be late. You might try restarting it. |
| must | strong obligation, certain deduction | You must sign here. He must be exhausted. |
| should | advice, expectation | You should rest. They should arrive by six. |
| will | future, prediction, willingness | It will rain. I'll carry that. |
| would | hypothetical, past habit, polite request | I would go if I could. Would you mind? |
| shall | offers and suggestions (I/we), formal future | Shall we begin? |
All 18 modals lessons
The pages in this section are organised by meaning rather than by word, because one modal usually has several jobs and one job is usually shared by several modals. Ability (can, could, be able to), permission (can, may, could), obligation (must, have to, should), possibility and deduction in the present and the past (may, might, could, must have), and the two most-searched single modals, would and could, each get their own page, with modal verbs as the overview.
- Would: Would is a modal verb, the past and conditional form of will. It has no -s form and is followed by a bare infinitive (she would go, not she would to go). Its core meaning is distance from reality: an imagined result (I would help), a softened request (Would you mind?), a habit that belongs to the past (we would swim every day), or a future seen from a past moment (she said she would call).
- Modal Verbs: Modal verbs are a small set of auxiliary verbs (can, could, may, might, will, would, shall, should, must) that add a speaker's judgement to the main verb: how possible, necessary, permitted, or certain something is. They share one grammar: no -s in the third person, no to before the following verb, and no do in questions and negatives. Each modal carries several meanings, and the context decides which one is meant.
- Could: Could is a modal verb with five everyday jobs: past ability, polite requests, present or future possibility, permission, and suggestions. It has one form for every subject, it is followed by a bare infinitive (could swim, not could to swim), and it builds negatives and questions without do. Which job it is doing depends on the context, not on a change of form.
- May vs. Might: May and might are modal verbs of possibility, and might is also the past and hypothetical form of may. In modern English they overlap heavily for guesses about now and later (It may rain. It might rain.). The useful differences that remain are register (may is more formal), remoteness (might can sound less likely or more tentative), permission (may I is still the formal grant; might I is rare and very polite), and past speculation (may have / might have plus a participle).
- Asking for Permission: English asks for permission with modal verbs and a few fixed phrases: can and could for everyday requests, may for formal ones, and is it all right if or do you mind if when you want a softer, more personal formula. The grammar is the same as other modal questions (modal + subject + bare infinitive), but the choice of form signals how polite or official the request is. Could here is about present politeness, not past time.
- Requests, Offers, and Invitations: Requests, offers, and invitations are three speech acts that share the same small set of modal patterns. To ask someone to do something you use Can you, Could you, Would you, or Would you mind. To offer to do something yourself you use I'll, I can, or Shall I. To invite someone into an activity you use Would you like to, Do you fancy, and How about. The grammar is simple; the choice among the forms is about how much room you leave the other person to refuse.
- Used To vs. Would: Used to and would both look back at habits that belong to an earlier time, but they are not interchangeable. Used to covers past actions and past states that are no longer true (I used to cycle to work; I used to own a canal boat). Would covers repeated past actions in a narrative, and it needs a past time frame around it (Every evening Grandad would wind the clocks). Would cannot describe a past state, which is the difference that decides most choices.
- Past Modals: Past modals are modal verbs followed by have and a past participle: must have, might have, may have, can't have, should have, could have, would have. English uses them for two jobs that ordinary past tenses cannot do: deduction about a past event you did not witness (She must have left; He can't have forgotten), and comment on a past action, as criticism, regret, or a missed chance (You should have called; We could have taken a taxi). The modal still carries the speaker's judgement; have plus the participle is what locates that judgement in the past.
- Modals of Obligation: Modals of obligation tell you how necessary an action is: a rule (must, have to, have got to), advice (should, ought to), or a practical need (need to). The negative side splits in two, and that split is the main trap: mustn't forbids an action, while don't have to and needn't say it is not required. Have to is not a true modal, but it does the same job as must and supplies the missing past and future forms.
- Past Ability and Permission: Past ability and past permission both use could, but could is not enough on its own. For a skill or freedom that existed over a period, could is the default (She could skate backwards; We could stay for the public session). For one specific achievement, especially a difficult one, English prefers was/were able to or managed to. Past permission also has was allowed to, which is clearer than could when the sentence could be read as ability instead.
- Modals of Possibility: Modals of possibility grade how sure the speaker is about a present situation: may, might, and could for a real chance, must for a confident deduction, and can't (or couldn't) for a confident 'that is impossible'. They occupy the finite slot (It might be interference; That can't be the pulsar). Maybe and perhaps are adverbs, not modals: they comment on the clause without changing the verb. This page is present deduction and present chance, not the three-word comparison of may, might, and could, and not past forms like must have.
- Will and Would: Will and would are a modal pair. Will looks at a real future, a promise, a spontaneous decision, or a present characteristic (I'll radio the quay. The hatch will slam in this wind.). Would is will held at a distance: an imagined result, a softer request, a future reported from the past, or a past habit (I'd radio if I had a spare battery. She said she would wait on the pontoon.). Same verb shape, one step further from now or from reality.
- Will Have and Would Have: Will have plus a past participle looks forward to a point and treats an action as already complete there (By dusk we will have pressed the last of the apples) or makes a confident deduction about now (They'll have stacked the crates by now). Would have plus a past participle looks back at a past that did not happen: the result half of a third conditional, or speculation about a missed chance (We would have finished sooner if the mill hadn't jammed). The two strings share a shape and split on time and reality.
- Can for Ability: Can and can't talk about present ability: what you know how to do, or what is possible for you now. She can solder. He can't swim a length of backstroke. Can does not take to, does not add -s, and does not have an infinitive or a past participle of its own, so English borrows be able to when a form of can cannot exist (I'd like to be able to crochet. She has been able to knead since she was twelve.). Can also asks for permission; that job has its own page.
- Present Modals: Present modals are can, must, may, might, should, and will used about now: ability (She can lift the crate), obligation (You must sign), possibility (It might jam), advice (You should bleed the radiator), and deduction (That will be the intern). The modal is followed by a bare infinitive, not by have plus a participle. Past judgement uses must have, might have, should have: that is a different page.
- Have To and Have Got To: Have to and have got to express obligation that comes from a rule, a timetable, or a situation, not from the speaker's own authority. Have to conjugates like an ordinary verb (have to, has to, had to, will have to) and uses do in questions and negatives. Have got to is a British present-tense variant (I've got to go) that inverts have and is not used for past or future. Neither form is a true modal; true modals such as must do not take do, to, or tense endings.
- May, Might, and Could: May, might, and could all mark possibility: a guess about now, later, or (with have plus a participle) the past. May is the most formal and often the most real-sounding chance. Might can sound slightly remoter or more tentative. Could as possibility, not ability, sits close to might (That could be the stage manager). The three overlap a great deal; the useful work is hearing could as a guess, not only as past or present ability.
- Making Suggestions: Suggestions in English are offers of an idea for what we, or you, might do. The usual frames are Let's, Why don't we, Why don't you, How about, What about, Shall we, We could, and I suggest. They are milder than instructions and different from requests, which ask the other person to do something for you. The grammar is a small set of patterns; the choice among them is about how much room you leave the other person to refuse.
Modals FAQs
- What are the nine modal verbs in English?
- Can, could, may, might, must, shall, should, will, and would. Ought to, need, and dare behave like modals some of the time and are often called semi-modals, together with have to and be able to, which express modal meanings with ordinary verb grammar.
- Why don't modal verbs take -s or to?
- Historically they were a separate class of verb that never developed those endings, and the grammar has stayed frozen. Practically, the rule is simple: the modal never changes (she can, not she cans) and the next verb is a bare infinitive (she can swim, not she can to swim). The exception is ought to, which keeps its to.
- What is the difference between must and have to?
- Both express strong obligation, but must usually comes from the speaker (I must call my mother, I feel I should) while have to comes from outside (I have to wear a uniform, the rule says so). In the negative they split completely: mustn't means it is forbidden, don't have to means it is not necessary.
- How do I talk about the past with a modal?
- For deduction and possibility, add have plus a past participle: he must have left, she might have forgotten. For ability, use could or was able to: I could swim at five, I was able to finish in time. For obligation, switch to had to, because must has no past form.
- Is could the past of can?
- Sometimes. I could swim when I was five is genuinely past ability. But could also works as a polite present request (Could you pass the salt?) and as present or future possibility (It could rain later). Treat could as its own modal with several meanings rather than as simply can in the past.