Modal verbs

In the English language, a modal auxiliary verb is an auxiliary verb (or helping verb) that can modify the grammatical mood (or mode) of a verb. The key way to identify a modal auxiliary is by its defectiveness; the modal auxiliaries do not have participles or infinitives.

The modal auxiliaries are as follows:

  • will and would
  • shall and should
  • may and might
  • can and could
  • must and have to
  • ought to and had better
  • used to
  • dare and need (Archaic use)
  • by some accounts, do

Each of these is treated here separately.


Would is originally the past tense of will, and it (or its contracted form ‘d) is still used in that sense: “In the 1960s, people thought we would all be driving hovercars by the year 2000.”

Its more common use, however, is to convey the conditional mood, especially in counterfactual conditionals; that is, to express what would be the case if something were different: “If they wanted to do it, they would have done it by now.” There is not always an explicit protasis (“if” clause) in this use: “Someone who likes red and hates yellow would probably prefer strawberries to bananas” means the same as, “If someone liked red and hated yellow, he or she would probably prefer strawberries to bananas.”

Would can also be used with no modal or temporal meaning, to affect either politeness or formality of speech:

  • “I would like a glass of water, please.”
  • “Would you be a dear and get me a glass of water?”
  • “It would seem so.”

All of these uses can be described as displaying remoteness: either remoteness of time (the past), remoteness of possibility (a conditional), or remoteness of relationship to the addressee (politeness or formality).


See also: Shall and will

Shall is used in many of the same senses as will (see above), though not all dialects use shall productively, and those that use both shall and will generally draw a distinction (though different dialects tend to draw different distinctions). In standard, perhaps old-fashioned, British English, shall in the first person, singular or plural, indicates mere intention, but in other persons shows an order, command or prophecy: “Cinderella, you shall go to the ball!” It is, therefore, impossible to make shall questions in these persons. Shall we? makes sense, shall you? does not.

Shall derives from a main verb meaning to owe, and in dialects that use both shall and will, the former is often used in instances where an obligation, rather than an intention, is expressed.


Should is to shall as would is to will, except that should is common even in dialects where shall is not.

In some dialects, it is common to form the subjunctive mood by using should: “It is important that the law should be passed” (where other dialects would say, “It is important that the law be passed”) or “If it should happen, we are prepared for it” (or “Should it happen, we are prepared for it”; where early Modern English would say, “If it happen, we are prepared for it,” and many dialects of today would say, “If it happens, we are prepared for it”).

Should commonly describes an ideal behavior or occurrence and imparts a normative meaning to the sentence; for example, “You should never lie” means roughly, “If you always behaved perfectly, you would never lie”; and “If this works, you should not feel a thing” means roughly, “I hope this will work. If it does, you will not feel a thing.” In dialects that use shall commonly, however, this restriction does not apply; for example, a speaker of such a dialect might say, “If I failed that test, I think I should cry,” meaning the same thing as, “If I failed that test, I think I would cry.”

May and might

May is used to indicate permission (“May I have a word with you?”) or possibility (“That may be.”), though in some dialects, the former use is often supplanted by can (see below), and the latter by might (which was originally its past tense), making this auxiliary rather uncommon in those dialects.

May is able to be used with either a present or a future sense: “I am not sure whether he is there now; he may not be, but even if he is not, he may go there later.” Theoretically speaking, might is the corresponding past-tense form, but since some dialects use might quite commonly with a present or future sense, it is more common to use may or might with the perfect aspect to provide a past sense: “He might have been gone when we got there, or he might have been hiding.”

May is also used to express irrelevance in spite of certain or likely truth: “He may be taller than I am, but he is certainly not stronger” may mean roughly, “While it is true that he is taller than I am, that does not make a difference, as he is certainly not stronger.” (However, it may also mean, “I am not sure whether he is taller than I am, but I am sure that he is not stronger.”) In many dialects, might is used in this sense as well.

In addition to what has already been mentioned, might also serves as the conditional mood of may: “If he were more polite, he might be better liked.” Also, while there are some dialects where the use of might to replace may is very common, even in colloquial or informal speech, there are other dialects where might serves a more polite or formal form of may, just as would does for will (see above) and could does for can (see below).

May and might do not have common negative contractions (equivalents to shan’t, won’t, can’t, couldn’t etc).

Can and could

Can is used to express ability (as in “I can speak English”, meaning “I am able to speak English” or “I know how to speak English”), permission (as in “Can I use your phone?” meaning “Do you permit me to use your phone?”), willingness (as in “Can you pass me the cheese?” meaning “Please pass me the cheese”), or possibility (“There can be a very strong rivalry between siblings”, meaning “There is sometimes a very strong rivalry between siblings”). (Some of these senses may be perceived as incorrect in some dialects; in particular, formal American English often prefers to use may when the sense is permission and could when the sense is willingness.) The negative of can is the single word cannot or the contraction can’t.

Could has at least three distinct functions. First, it can often replace can, although generally it gives the phrase a conditional tone. For example, “I can help you with your work” suggests that the speaker is ready and willing to help, whereas “I could help you with your work” gives a more tentative sense of ability to help. In this sense, could is often used like a conditional: “I could help you if you helped yourself.”

Second, could functions as a kind of past tense for can, though could does not function grammatically like any regular past simple verb.

Third, could carries the same meaning as might or may in the present. That is, could suggests that something is a possibility. For instance, John is not in the office today, he could be sick. In this phrase, might or may would carry the same meaning. Note that can in the negative carries the same idea as couldn’t in this sense: “He cannot have left already; why would he want to get there so early?” Also, note that when regarding potential futures actions could is not equivalent to might or may. “I might go to the mall later,” does not have the same connotations as “I could go to the mall later,” which suggests ability more than possibility.

Must and have to

Must and Have to are used to express that something is imperative or obligatory (“He must leave”). According to many scholars, the difference between mus and have to is found in the source of the obligation.[citation needed] Must is said to be chosen when the obligation stems from an internal source (i.e. an obligation one imposes on oneself); have to when the source is external (i.e. your boss, rules, the law, an authority figure, etc). Compare “I have to finish this report today” (where there is a deadline, which I did not set) with “I must finish this report today” (I am imposing my own deadline).

In negative constructions, there is a different distinction between must and have to. Must not (or mustn’t) indicates a prohibition (“you must not smoke in here”) or a resolution not to do something (“I mustn’t make that mistake again”), whereas do not have to (or don’t have to) indicates that there is not an obligation either to do or to not do the verb in the sentence (“you don’t have to go if you don’t want to”).

Both must and Have to are also used to express a strong belief that something is the case, but makes it clear that the speaker is not stating a fact but an opinion (“It must be here somewhere”). The basis of this belief is not factual but logical. In other words, we are speculating based on what we know about the world and how it works (i.e. what has happened in the past, someone’s character, etc).

Ought to and had better

Ought to and had better are synonymous with one of the senses of should: it is used to express an ideal behavior or occurrence or suggested obligation. In dialects that use shall commonly, should has a wide array of meanings, so ought is very common (as it is more precise), as is ought not (or oughtn’t). In other dialects, ought may or may not be common, but ought not is generally quite rare: the opposite of “You ought to tell him how you feel” is generally “You should not tell him how you feel,” or “You had better not tell him how you feel.” There is no negative contraction for had better. Had better not is used at all times. In speech, the had in had better is generally disregarded.

Used to

Used to is a modal construction signifying a past tense, used to discuss past states or habits which are no longer current. For example, “I used to go to college” suggests that that the speaker no longer goes to college. Negative constructions of used to usually follow did not (or didn’t) used to (“she didn’t used to like me”). Other variants are sometimes used, such as “she used not to like me” or “she used to not like me”, although these may be regarded as non-standard by some acadamics, especially the used to not construction, which employs a split infinitive.

Dare and need

Nowadays, dare and need are not commonly used as auxiliaries, but formerly, both were. Dare is especially rare in common parlance, with the notable exception of “How dare you!”. “He dare not do it” is equivalent to today’s “He does not/will not/would not dare to do it,” while “It need not happen today” is equivalent to today’s “It does not need to happen today” or “It might not happen today.” However, in the sentence “I need to lose weight,” need is not being used as an auxiliary since it can be conjugated to other forms: “I needed to lose weight,” “I have been needing to lose weight,” etc.


As an auxiliary, do is essentially a “dummy”; that is, it does not generally affect the meaning. It is used to form questions and negations when no other auxiliary is present: “I don’t want to do it.” It is also sometimes used for emphasis: “I do understand your concern, but I do not think that will happen.” Also, do sometimes acts as a pro-verb: “I enjoy it, I really do [enjoy it], but I am not good at it.” (Other auxiliaries do this as well: “I can do it, I really can [do it], it just takes me longer”; but it bears particular note that in the case of do, it is often used as a pro-verb when it would be absent if the verb were present.) Because it does not affect the meaning of its verb, not all grammarians acknowledge do as a modal auxiliary. In a sense, it indicates a lack of modal auxiliary. (Do is also different in that it has a distinct third-person singular form, does, and in that its past tense, did, is used exactly as a past tense, not as a more general remote form).

Double modal

In standard English usage, it is rare to use more than one modal verb consecutively, with a few exceptions such as might have to or may have used to. A greater variety of double modals appear colloquially in some regional or archaic dialects. In the southern United States, for example, phrases such as might could or ought to should are sometimes used in conversation.[1][2] The double modal may sometimes be redundant, as in “I ought to should do something about it”, where ought to and should are synonymous and either one could be removed from the sentence. In other double modals, the two modal verbs convey different meanings, such as “I might could do something about it tomorrow”, where might indicates the possibility of doing something and could indicates the ability to do it.

An example of the double modal used to could can be heard in country singer Bill Carlisle’s 1951 song “Too Old to Cut the Mustard”:

I used to could jump just like a dear,

But now I need a new landing gear.

I used to could jump a picket fence,

But now I’m lucky if I jump an inch.[3]

These kind of double modal phrases are generally not regarded as correct grammar,[1] although other double modals may be used instead. “I might could do something about it” is more often expressed as “I might be able to do something about it”, which is considered more grammatical, although in fact it is still a double modal: be able to is used here as a modal verb synonymous with could or can. Similarly used to could is usually expressed as used to be able to. Double modals can also be avoided by replacing one of the modal verbs with an appropriate adverb, such as using probably could or might possibly in place of might could.[2]

What are Modal Verbs?

Modal verbs are special verbs which behave very differently from normal verbs. Here are some important differences:

1. Modal verbs do not take “-s” in the third person.


  • He can  speak Chinese.
  • She should  be here by 9:00.

2. You use “not” to make modal verbs negative, even in Simple Present and Simple Past.


  • He should not be late.
  • They might not come to the party.

3. Many modal verbs cannot be used in the past tenses or the future tenses.


  • He will can go with us. Not Correct
  • She musted study very hard. Not Correct

Common Modal Verbs

Ought to

For the purposes of this tutorial, we have included some expressions which are not modal verbs including had better, have to, and have got to. These expressions are closely related to modals in meaning and are often interchanged with them.


“Can” is one of the most commonly used modal verbs in English. It can be used to express ability or opportunity, to request or offer permission, and to show possibility or impossibility.


  • I can ride a horse. ability
  • We can stay with my brother when we are in Paris. opportunity
  • She cannot stay out after 10 PM. permission
  • Can you hand me the stapler? request
  • Any child can grow up to be president. possibility


“Could” is used to express possibility or past ability as well as to make suggestions and requests. “Could” is also commonly used in conditional sentences as the conditional form of “can.”


  • Extreme rain could cause the river to flood the city. possibility
  • Nancy could ski like a pro by the age of 11. past ability
  • You could see a movie or go out to dinner. suggestion
  • Could I use your computer to email my boss? request
  • We could go on the trip if I didn’t have to work this weekend. conditional


“Might” is most commonly used to express possibility. It is also often used in conditional sentences. English speakers can also use “might” to make suggestions or requests, although this is less common in American English.


  • Your purse might be in the living room. possibility
  • If I didn’t have to work, I might go with you. conditional
  • You might visit the botanical gardens during your visit. suggestion
  • Might I borrow your pen? request


“Should” is most commonly used to make recommendations or give advice. It can also be used to express obligation as well as expectation.


  • When you go to Berlin, you should visit the palaces in Potsdam. recommendation
  • You should focus more on your family and less on work. advice
  • I really should be in the office by 7:00 AM. obligation
  • By now, they should already be in Dubai. expectation


“Must” is most commonly used to express certainty. It can also be used to express necessity or strong recommendation, although native speakers prefer the more flexible form “have to.” “Must not” can be used to prohibit actions, but this sounds very severe; speakers prefer to use softer modal verbs such as “should not” or “ought not” to dissuade rather than prohibit.


  • This must be the right address! certainty
  • Students must pass an entrance examination to study at this school. necessity
  • You must take some medicine for that cough. strong recommendation
  • Jenny, you must not play in the street! prohibition


“Would” is most commonly used to create conditional verb forms. It also serves as the past form of the modal verb “will.” Additionally, “would” can indicate repetition in the past.


  • If he were an actor, he would be in adventure movies. conditional
  • I knew that she would be very successful in her career. past of “will”
  • When they first met, they would always have picnics on the beach. repetition


“Will” is used with promises or voluntary actions that take place in the future. “Will” can also be used to make predictions about the future.


  • I promise that I will write you every single day. promise
  • I will make dinner tonight. voluntary action
  • He thinks it will rain tomorrow. prediction

Have To

“Have to” is used to express certainty, necessity, and obligation.


  • This answer has to be correct. certainty
  • The soup has to be stirred continuously to prevent burning. necessity
  • They have to leave early. obligation


“May” is most commonly used to express possibility. It can also be used to give or request permission, although this usage is becoming less common.


  • Cheryl may be at home, or perhaps at work. possibility
  • Johnny, you may leave the table when you have finished your dinner. give permission
  • May I use your bathroom? request permission


“Shall” is used to indicate future action. It is most commonly used in sentences with “I” or “we,” and is often found in suggestions, such as “Shall we go?” “Shall” is also frequently used in promises or voluntary actions. In formal English, the use of “shall” to describe future events often expresses inevitability or predestination. “Shall” is much more commonly heard in British English than in American English; Americans prefer to use other forms, although they do sometimes use “shall” in suggestions or formalized language.


  • Shall I help you? suggestion
  • I shall never forget where I came from. promise
  • He shall become our next king. predestination
  • I’m afraid Mr. Smith shall become our new director. inevitability

Ought To

“Ought to” is used to advise or make recommendations. “Ought to” also expresses assumption or expectation as well as strong probability, often with the idea that something is deserved. “Ought not” (without “to”) is used to advise against doing something, although Americans prefer the less formal forms “should not” or “had better not.”


  • You ought to stop smoking. recommendation
  • Jim ought to get the promotion. It is expected because he deserves it.
  • This stock ought to increase in value. probability
  • Mark ought not drink so much. advice against something (notice there is no “to”)

Had Better

“Had better” is most commonly used to make recommendations. It can also be used to express desperate hope as well as warn people.


  • You had better take your umbrella with you today. recommendation
  • That bus had better get here soon! desperate hope
  • You had better watch the way you talk to me in the future! warning

Have Got To

“Have got to” is used to express necessity and obligation.


  • Drivers have got to get a license to drive a car in the US. necessity
  • I have got to be at work by 8:30 AM. obligation

Modal Forms

Modal verbs can be used in a variety of different forms. Study the examples below.

Modal Simple
I could swim at the beach. Modal Continuous
I could be swimming at the beach right now. Modal Perfect
I could have swum at the beach yesterday. Modal Perfect Continuous
I could have been swimming at the beach instead of working in the office.
Passive Modal Simple
The room should be cleaned once a day. Passive Modal Continuous
The room should be being cleaned now. Passive Modal Perfect
The room should have been cleaned yesterday. Passive Modal Perfect Continuous
The room should have been being cleaned but nobody was there. (Rare form)