Mr.Maru: Are you still watching the World Cup?
Sparky: Yeah. It's the quarterfinals.
Mr.Maru: You have to study though.
Sparky: I don't have to study. I'll pass the test.
Mr.Maru: I don't think so. You should study.
Sparky: I'll do it later. You must make me dinner now.
Mr.Maru: I don't think so.
Sparky: You're my master. You have to make me food.
Mr.Maru: I'll do it later.

When do you use have to and when do you use must?  What is the difference between have to and must?  Let's talk about some examples and some rules for these two words.

Have to - Basic Usage

We use 'have to' when you are required to do something.  The person or thing that is requiring you to do something is external or not you.  This is usually used when you are asked to do something or you are required to do something for your job or for a situation.  For example,

I have to wear a suit to work every day.  (My company requires me to wear a suit every day.  If I don't wear a suit, I will get fired.)
He has to study for the test.  (He is required to study for the test.  If he doesn't study, he will not pass the test.)
Jenny has to fix the computer.  (It is her job to fix the computer, so she is required to fix it.)

Must - Basic Usage

We use 'must' in the same way.  The difference is that usually the person or force requiring you to do something is you.  You are pushing yourself to do the task not somebody or something else.  For example,

I must start exercising.  I'm starting to get fat. (I feel like I should start exercising because I'm getting fat.  Nobody told me to exercise.)
I must write these cards.  (I feel like I should write these cards because I might not have time later to write them.)

Another way to think of 'must', is that it is a reminder to oneself.  For example,

I must pay these bills.  I keep forgetting!

Have to vs. Must - Is there a big difference?

There is not a very big difference between these two.  In general, in American English 'must' is used less often than 'have to'.  American English usually uses it only to take about yourself.  The subject is usually 'I' for sentences that use 'must'.  Lots of times, 'must' and 'have to' can be used in the same place and have the same meaning. For example,

I must buy some new shoes.
I have to buy some new shoes.

There is not a big difference between these two sentences.  However, using 'must' has more of an internal desire or feeling to do something.

Do you think you understand?  Let's take a short quiz.  Please choose the best answer for each.

1) I ______ brush my teeth every day.  If I don't I will get cavities.

A) have to
B) must

2) I _____ stop smoking.  It's such a bad habit.

A) have to
B) must

3) George _______ work on Sunday, so he can't come to the picnic.

A) has to
B) must

Answers

1) A) - A) is the best answer because there is an external pressure.  If I don't I will get cavities.
2) B) - B) is the best answer (A) is also possible) because it is mostly an internal feeling.  It's such a bad habit. I feel like I should stop smoking.
3) A) - A) is the best answer because his company is telling him to work.

Thanks for stopping by, If you have any questions about English grammar, please email me at This e-mail address is being protected from spambots. You need JavaScript enabled to view it and have fun watching the World Cup!