Must and Have to

What's the difference between must and have to?

Must and have to are modal verbs in English. This page will guide you to the proper use of these modals.

Must

1. We use must to make a logical deduction based on evidence. It indicates that the speaker is certain about something:
Examples:

• It has rained all day, it must be very wet outside.
• The weather is fantastic in California. It must a lot fun to live there.

2. Must is also used to express a strong obligation.
Examples:

• Students must arrive in class on time.
• You must stop when the traffic lights are red.
• I must go to bed.

Have to

Like must, have to is used to express strong obligation, but when we use have to there is usually a sense of external obligation. Some external circumstance makes the obligation necessary.
Examples:

• I have to send an urgent email.
• I have to take this book back to the library.