Have to and Must

have to and mustYou must not park your car in an area where the ‚No Parking‘ sign applies.

Must is not used very often in American English in everyday conversations. It’s considered to be a rather strong word and is best reserved for rules and personal obligations. This post will explain when to use have to and must.


  • ‚Have to‘ and ‚must‘ are very similar and can both express an obligation or that something is necessary. Though in American English, ‚have to‘ is more common.


It’s getting late and I must/have to go.

I must/have to wear reading glasses otherwise I can’t read.

  • Both ‚have to‘ and ‚must‘ can be used for rules. ‚Must‘ sounds more formal and is often used in written rules.


You must/have to use a pen to fill out the form.

We must receive your application no later than June 30th.

  • ‚Have to‘ and ‚must‘ can also be used to give your opinion about something.


I haven’t called my mother in a long time. I must/have to call her.

You must/have to see this new movie – it’s phenomenal.

  • ‚Have to‘, not ‚must‘, is usually used to say what someone else is obliged to do.


You have to be to work by 8 am.

James has to take his medicine everyday.

  • ‚Must‘ is used to express probability as well.


You must feel upset by the news.

She must not know about the meeting. Maybe that’s why she’s not here yet.

  • We often use must in questions when being critical.

Must you always have the TV on so loud?

Must you talk so loud?

  • In the negative forms, ‚must not‘ and ‚don’t have to‘ have completely different meanings.


You mustn’t park here. (mustn’t = not allowed)

You don’t have to go to the meeting if you are too busy. (don’t have to = you don’t need to do something)