Modal Verbs in English

Definition and Examples

modal verbs
The core modals in English. sorendls/Getty Images

In English grammar, a modal is a verb that combines with another verb to indicate mood or tense. A modal, also known as a modal auxiliary or modal verb, expresses necessity, uncertainty, possibility, or permission.

Modal Basics

Struggling to understand how modal verbs function in English is entirely normal as their range of applications is quite broad. Even advanced students and native speakers struggle to use these irregular verbs from time to time.

With that said, practice is important and the best place to start is by finding out which verbs are considered modals. There are two types of modal verbs: pure modals and semimodals. There are also modal phrases.

Pure Modals

Pure modals never change their form regardless of subject and don't change to show past tense. These verbs can express certainty or suggestion. Pure modals are followed by a bare infinitive, an infinitive verb without "to". See below for examples. ​

  • I can sing. Bob can sing. I found out they can sing.
    • Modal verbs can also be used in the negative by adding "not", as in I can not sing.
  • I should go. She should go. We should go.

Most linguists agree that there are 9 pure or core modals in English:

  • can
  • could
  • may
  • might
  • must
  • shall
  • should
  • will
  • would

Unlike other auxiliaries, common modals have no -s, -ing, -en, or infinitive forms. Modals such as "ought" that require a "to"-infinitive complement are regarded as marginal modals, also called semimodals.


Semimodals or marginal modals are used to imply a range of possibilities, obligations, necessity, or advice. Notice that these verbs can be conjugated by subject and tense.

  • I need to take responsibility for my actions. She needs to take responsibility for her actions. They needed to take responsibility for their actions.
  • You ought to know better by now.

The four semimodals generally agreed upon are:

  • need (to)
  • ought (to)
  • used (to)
  • dare (to)

Some experts also include have (to) and be able (to) in this list.

Modal Phrases

To further complicate an already confusing subject, phrases with modal meaning can be constructed without the use of a standard modal or semimodal verb. Sometimes, other verbs and phrases—including had better and invariant be—also function as modals or semimodals.

Modal Usage and Examples

Modals are commonly used to express your degree of certainty about an outcome or the possibility of something. When using modals, keep in mind that they should always appear first in a verb phrase. Consider these two examples:

  • Kim must be his sister because they look just like each other.
  • I will probably be there, but I can't make any promises.
  • You should go to that cafe some time, I think you'd really like it.

In the first example, the speaker is making a statement as if it were a matter of fact. In the second example, the statement implies a degree of uncertainty that excuses the speaker from an obligation.

The same modal verbs that can be used to express only some certainty or possibility can also express absolute conviction and resolve, which makes mastering modals tricky. For example, consider the modal verb should go and how it's used in this sentence:

  • The bank closes in 15 minutes. We should go there now.

This modal is now expressing a strong degree of obligation. The speaker knows they need to go to the bank if they're going to get there before it closes.

Famous Quotes

As you become more proficient in English, you'll discover just how frequently modals are used. Take a look at these examples from famous people.

  • "When I was younger I could remember anything, whether it happened or not." -Mark Twain
  • "She thought, 'I must hurry before the robbers come.'" -Jean Stafford
  • "[G]overnment of the people, by the people, for the people, shall not perish from the earth." -Abraham Lincoln


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Your Citation
Nordquist, Richard. "Modal Verbs in English." ThoughtCo, Jul. 31, 2021, Nordquist, Richard. (2021, July 31). Modal Verbs in English. Retrieved from Nordquist, Richard. "Modal Verbs in English." ThoughtCo. (accessed June 8, 2023).