I Swear English › Modal Verbs › Must vs Have To
How to form the must vs have to
Must is for internal obligation, what we want to do.
Have to is for external obligation, what somebody else wants us to do.
The following video explains The Difference between Must and Have to:
When to use it
- Must — obligation that feels personal or internal, and strong recommendations. I must call my mother. You must see this film!
- Have to — obligation from an outside rule or authority. I have to wear a uniform at work.
Signal words & time expressions: at work, by law, the rules, my own choice
Watch the video lesson
Video transcript
Must and Have to, what's the difference? OK. Must is talking about internal obligation. What you personally want. What your personal circumstances dictate. As a contrast have to talks about external obligations. What external circumstances force us to do. What somebody else wants us to do. So for example: soldiers have to obey orders. Ok. It's an order so they have to obey. We use must for thin... when we want to talk about things we want, or think are good. So notice for example: Perhaps you go to the doctor. And somebody asks what the doctor said. You could say, the doctors said I have to give up smoking, or the doctor said I must give up smoking. Have to, what the doctor wants. Must, what I want. OK. SO in one I want to give up, and one I don't really. For example: when it's time to leave a place, perhaps we say, "I must go." "I have to go." I must go, it implies I need to go. I'm tired, I need to go to sleep. I want to go. I have to go, there is an external circumstance meaning that I have to go. Perhaps I'm late. Or I don't want to be sleepy at work tomorrow. So there you are, must and have to. Must for internal obligations, have to for external ones. Thanks for watching and I'll see you in another video. Bye for now.
Common mistakes to avoid
| Not quite… | Better |
|---|---|
| I | I must go. — must takes the base verb, no to. |
| Yesterday I | Yesterday I had to work late. — must has no past form; use had to. |
Frequently asked questions
Is there a real difference between ‘must’ and ‘have to’?
Often they're interchangeable. The traditional rule: must = the obligation comes from the speaker; have to = it comes from outside (a rule, a boss, the law).
What's the past of ‘must’?
Had to: I had to leave early. Must itself has no past form for obligation.
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This lesson is part of our free English Modal Verbs course — work through it in order or jump to what you need next.