What is a Modal Verb? Definition, Usage & Examples

Discover what a modal verb is, find out how to use modal verbs, and see clear examples of modal verbs in use to improve your grammar skills.

Modal verbs are essential in English. They help express ability, permission, possibility, necessity, or advice. Unlike a regular verb, modal verbs don’t change form based on the subject. They are followed by the base form of a verb without “to”. For example:

You can run.
She must do her work.

This article explores the definition, common uses, and examples of modal verbs. You’ll learn how to use them effectively in different contexts.

Modal verbs are auxiliary verbs (helping verbs) that modify the main verb in a sentence. They express various meanings like ability, permission, possibility, necessity, or advice. Examples of modal verbs include “can,” “could,” “may,” “might,” “must,” “shall,” “should,” “will,” and “would.”

Unlike other verbs, modal verbs do not change form based on the subject, and they don’t need an auxiliary verb to form questions or negatives.

For example:

Can you swim?
You must finish your homework.
We might go to the park later.

Modal verbs also lack infinitive forms or past participles. This makes them different from other auxiliary verbs like “have” or “be.”

Modal verbs share some unique characteristics:

No Infinitive or Past Participle: You never use “to” before a modal verb, and they don’t have past participles.
- Incorrect: To can swim.
- Correct: Can swim.
Followed by the Base Form: Modal verbs are always followed by the base form of the main verb.
- Example: He can play the guitar.
Same Form for All Subjects: Modal verbs don’t change based on the subject.
- Example: I can swim. She can swim.
Negatives Without “Do”: To form the negative, simply add “not” after the modal verb.
- Example: He cannot drive.
Questions Without “Do”: Questions are formed by placing the modal verb before the subject.
- Example: Can you help me?

1. Can

Can is used to express ability, permission, or possibility.

Ability: You use “can” to describe what someone is capable of doing.
- Example: I can speak French.
Permission: It’s also used to ask or give permission.
- Example: Can I leave early?
Possibility: “Can” sometimes refers to the possibility of something happening.
- Example: The weather can change quickly.

2. Could

Could is the past tense of “can” and expresses ability in the past, polite requests, or possibility.

Past Ability: Use “could” to talk about something you were able to do in the past.
- Example: When I was young, I could run fast.
Polite Request: It makes requests sound more polite or formal.
- Example: Could you help me with this?
Possibility: “Could” also suggests a possibility in the future.
- Example: It could rain later.

3. May

May expresses permission or possibility, often in formal contexts.

Permission: It’s used to ask or give formal permission.
- Example: May I use your phone?
Possibility: “May” also refers to something that might happen.
- Example: It may snow tonight.

4. Might

Might is often used as a more tentative or uncertain form of “may.”

Possibility: You use “might” when you’re unsure if something will happen.
- Example: We might go to the party.
Suggestions: It can also be used to offer advice indirectly.
- Example: You might want to rethink your decision.

5. Must

Must expresses strong obligation or necessity. It can also indicate logical conclusions.

Obligation: You use “must” when something is required.
- Example: You must wear a helmet while riding a bike.
Deduction: It’s also used to make logical assumptions.
- Example: He must be at work, as his car is missing.

6. Shall

Shall is used for formal suggestions, offers, or future actions. It’s common in British English.

Suggestions: “Shall” is used to ask for opinions or offer suggestions.
- Example: Shall we go for a walk?
Future Action: In formal contexts, “shall” is used to express future actions.
- Example: We shall meet again tomorrow.

7. Should

Should is used for giving advice, recommendations, or expressing expectations.

Advice: “Should” suggests what is advisable or recommended.
- Example: You should study for the test.
Expectation: It can also imply what is expected or likely.
- Example: They should arrive by noon.

8. Will

Will is used to express future actions, promises, or willingness.

Future Action: It’s commonly used to describe something that will happen in the future.
- Example: I will call you tomorrow.
Promises: It’s also used to make promises or commitments.
- Example: I will help you with your project.

9. Would

Would is the past tense of “will” and is used for polite requests, hypothetical situations, or past habitual actions.

Polite Request: “Would” makes requests more polite.
- Example: Would you like some coffee?
Hypothetical Situations: It is often used in conditional sentences to express hypothetical situations.
- Example: If I won the lottery, I would buy a house.
Past Habit: It describes past habitual actions.
- Example: When I was a child, I would play outside for hours.

When Are Modal Verbs Used?

You use modal verbs to show your attitude toward an action or situation. They express possibility, ability, permission, necessity, or certainty. Understanding when to use them helps you communicate more accurately and confidently.

To Show Ability

Modal verbs express what someone is capable of doing. You use can and could for this purpose.

She can speak three languages.
I could swim when I was a child.

To Show Possibility or Probability

You use modal verbs to talk about how likely something is to happen. May, might, and must often express degrees of certainty.

It may rain later.
They might be at the park.
You must be tired after your trip.

To Give Permission or Make Requests

Modal verbs help you ask or grant permission politely. Can, could, and may are commonly used in this way.

Can I borrow your notes?
You may go home now.
Could you open the window, please?

To Express Obligation or Necessity

You use modal verbs to show that something is required, necessary, or expected. Must, have to, and should often serve this role.

You must wear a seatbelt.
I have to finish my project today.
You should study for the exam.

To Offer or Suggest Something

Modal verbs make offers or suggestions sound polite and natural. Shall and could are often used in this way.

Shall we go for lunch?
You could try calling her again.

To Make Predictions or Promises

You use will and would to talk about future actions, make predictions, or express determination.

I will call you tomorrow.
It won’t take long.

To Give Advice or Recommendations

Modal verbs can express advice or suggestions in a friendly and encouraging tone. Should and ought to are useful here.

You should eat healthier.
You ought to rest more.

To Express Habits or Past Routines

You use used to to describe past habits or situations that no longer happen.

I used to play football every weekend.

Modal verbs make forming questions easier. Instead of using “do” or “does,” place the modal verb at the beginning of the sentence.

Examples:

Can you drive?
Should I call her?
Will they come to the meeting?

These structures help you avoid confusion and make your questions more natural.

To create negative sentences with modal verbs, simply add “not” after the modal. Some modals have contracted forms, making them easier to use in conversation.

Examples:

You should not (shouldn’t) skip meals.
He cannot (can’t) swim.
We might not (mightn’t) see her today.

These negative forms are key to expressing what’s not allowed, possible, or advisable.

Learning how to use modal verbs is essential, but mistakes can happen. Here are a few common errors and how to avoid them:

1. Using the Wrong Form of the Main Verb

Always follow modals with the base form of the main verb, not the infinitive or past tense.

Incorrect: I can to go to the store.
Correct: I can go to the store.

2. Misusing “Can” and “May” for Permission

Use “can” for informal permission and “may” for more formal contexts.

Informal: Can I leave now?
Formal: May I be excused?

3. Forgetting the “Not” in Negatives

When making negative statements, don’t forget to include “not” after the modal verb.

Incorrect: You should go if you’re sick.
Correct: You should not go if you’re sick.

Conclusion

Modal verbs are vital tools in English, helping you express everything from ability to obligation. Whether you’re giving advice with “should,” asking permission with “may,” or talking about future plans with “will,” modals are crucial for fluent communication.

Practice using modal verbs in different situations, and soon, they’ll become second nature. Start applying them in your conversations, emails, or essays, and you’ll see how much they can enhance your communication!