Have to vs Must in English: Rules, Examples, and Exercises

11/10/2025 Learning & Grammer created by Sprachcaffe Team

This article explains the difference between "Must" and "Have to" very clearly, with examples and practical exercises.

The English language has many specific verbs, which have a precise meaning and are used in certain circumstances: among these, we find have to and must.

Although the meanings may seem similar—if not almost the same—in reality there is a clear difference between must and have to, which are therefore not interchangeable.

When to use one? And when to use the other?

It may seem counterintuitive at first, but you'll see that after this detailed—and also simple!—lesson, you'll have a clear understanding of how to use these two verbs and how to apply them independently in sentences and speeches.

To help you even further, we at Sprachcaffe will test you with a couple of exercises using must and have to at the end of the lesson so you can test the skills you've just acquired and understand whether the topic is completely clear to you or not.

Let's get started!

What Are ‘Have to’ and ‘Must’ in English?

"Have to" and "must" are two verb forms used in English to express obligation, necessity, or duty.

We translate them, therefore, with the verb "dovere" (to have to), or with its synonyms such as "it is necessary" or "it is necessary", depending on the circumstances.

More specifically, must is a modal verb , a type of auxiliary verb used in English to express modalities such as obligation, possibility, ability, permission, and other conditions. Modal verbs don't function like main verbs because they don't change form (they don't have a past tense, participle, or gerund form) and are always followed by the base form of another verb (the infinitive without "to").

Instead, have to is a verbal construction that always indicates obligation or necessity, often perceived as coming from an external source, such as rules, laws, or situations.

Although they are often interchangeable, there are some important differences in their use that are worth noting.

When to use 'Must?'

Let's first see when to use must, that is, the situations and contexts in which this verb is the most correct choice:

Personal or internal obligation : Used when the speaker feels something is necessary or obligatory.
Example: I must call my mother. → I must call my mother.
Speaker-imposed rules and instructions : Indicates that the obligation is imposed by the speaker.
Example: You must finish your homework before playing.
Negative form for prohibitions : "Must not" (mustn't) is used to express official prohibitions and bans.
Example: You must not smoke here.
General and universal uses : It is also often used to talk about general truths or needs that are considered mandatory.
Example: All visitors must sign in at the reception.
Lack of past tense : It cannot be used in the past, so it is not used for past obligations. In these cases, "had to" is used.
Example (past): I had to call my mother yesterday.

Difference Between 'Must' and 'Have to'

At this point, it is clear that there is a difference between must and have to: although they are both used to express obligation or necessity, they are not used in the same cases, but each fulfills specific tasks.

"Must" : Indicates an obligation that is perceived as more personal or internal. It is often used for obligations that the speaker feels strongly about.
"Have to" : Indicates an obligation that is perceived as external or imposed by a situation, rule, or authority.

Difference between "Must" and "Have to":

"Must" and "have to" are both used to express obligation or necessity, but they differ in nuances of meaning and context of use.

When to use 'Have to?'

And now, let's see when it is necessary to use the verb have to:

External or other-imposed obligation : The verb have to indicates an obligation that comes from an external source, such as laws, rules, or situations.
Example:
I have to go to work early tomorrow.
Daily needs and necessities : It is often used to express obligations in everyday situations. Example: You have to wear a uniform at school.
Negative form for lack of obligation : The negative form "Don't have to" is used to indicate that something is unnecessary.
Example:
You don't have to come if you don't want to. → You don't have to come if you don't want to.
Past and future tense : It can be used in the past (had to) and future (will have to) to express obligations even in these verb tenses.
Example (past):
I had to finish the report by yesterday.
Example (future):
I will have to study harder next semester.

Exercises with 'Must' and 'Have to'

What do you say, should we check if everything is really clear and if you can move on to the next topic without a hitch?

Here are a couple of exercises with musts and must-haves to test your newly acquired skills. You'll also find the solutions to the two exercises at the bottom. But don't peek, there's no grade to get or competition to win.

Use these exercises to test your knowledge and let us know how it goes!

Exercise 1: Complete the sentences with "must" or "have to"

You _______ wear a uniform at this school.
I _______ finish this project by tonight. → I have to finish this project by tonight.
We _______ be at the airport two hours before the flight. → We need to be at the airport two hours before the flight.
She _______ not talk during the movie. → She must not talk during the movie.
They _______ leave early because of the traffic.
You _______ listen to the teacher. → You must listen to the teacher.
He _______ take his medicine every day. → He must take his medicine every day.
I _______ call my boss before 10 AM. → I have to call my boss before 10 AM.
We _______ not forget to lock the door. → We must not forget to lock the door.)
She _______ be home by midnight. → She must be home by midnight.)

Exercise 2: Rewrite the sentences using "must" or "have to"

It is necessary for you to study for the exam.
You _______ for the exam. (You have to study for the exam.)
It is required by law that drivers carry a license.
Drivers _______ a license. (Drivers must have a license.)
There is a rule that says employees cannot smoke in the office.
Employees _______ in the office. (Employees should not smoke in the office.)
It's your own decision to stop eating junk food.
You _______ stop eating junk food. (You need to stop eating junk food.)
The teacher says that students need to hand in their assignments by Friday.
Students _______ their assignments by Friday. (Students must hand in their homework by Friday.)
It's important that you arrive on time.
You _______ on time. (You must arrive on time.)
It's necessary for her to finish the report today.
She _______ the report today. (He has to finish the report today.)
It's prohibited to park here.
You _______ here. (You don't have to park here.)
It's essential that we conserve water.
We _______ water. (We must conserve water.)
It's not necessary for you to wait for the meeting if you're busy.
You _______ the meeting if you're busy. (You don't have to attend the meeting if you are busy.)

These exercises will help you practice using "must" and "have to" in various contexts and better understand the differences between the two verbs. Here you'll find the solutions to both.