Have To vs. Must vs. Should
'Have to,' 'must,' and 'should' talk about different levels of obligations that may confuse you. In this lesson, we will learn more about them.
What Is Their Main Difference?
The main difference between 'have to,' 'must,' and 'should' is that 'must' and 'should' are modal verbs while 'have to' is a semi-modal verb.
Semi-modal Have to
'Have to' is a semi-modal verb (also known as semi-modals). Semi-modals function similarly to modals. They sometimes act like modals and sometimes act like a main verb. It is used to express obligations, certainty, etc. For instance:
Modal Verb Must
'Must' is a modal verb (also known as modals). Modals give additional information about the main verb of the sentence. 'Must' expresses obligations, likely events, and suggestions. Have a look:
Modal Verb Should
'Should' is a modal verb. 'Should' is used to talk about obligations, assumptions, and to give advice. For example:
Talking about Obligations
'Have to,' 'must,' and 'should' are used to talk about different levels of obligations:
- 'Have to' talks about obligations that are self-motivated. Leaving such obligations unfulfilled may not have consequences.
- 'Must' talks about obligations that are assigned by law, society, or someone else. Disobeying such obligations will lead to a penalty or punishment.
- 'Should' expresses obligations mainly when we are criticizing others.
While the affirmative form of 'have to,' 'must,' and 'should' have the same meaning, their negative forms convey different meanings.
- The negative form of 'have to,' 'don't have to' is used to say that fulfilling something is not a must and more of a suggestion.
- The negative form of 'must,' 'must not' expresses absolute obligation.
- The negative form of 'should,' 'shouldn't' shows that doing something is better to be avoided.
Formality and Frequency
The table below illustrates the frequency of 'have to,' 'must,' and 'should' in formal and informal contexts.