Should vs. Have To

'Should' and 'have to' are confused by learners as they both express a level of certainty. In this lesson, we will learn more about them.

What Is Their Main Difference?

The main difference between 'should' and 'have to' is that 'should' is modal verb while 'have to' is semi-modal verb.

'Should' is a modal verb. Modal verbs (also known as modals) are used to give additional information about the main verb. 'Should' is used to talk about assumptions and to give advice. It is the past tense of modal verb 'shall.' For example:

He should have forgotten to take his travel mug.

She should ask Nina to help her.

'Have to' is a semi-modal. Semi-modals function similarly to modals. They sometimes act like modal verbs and sometimes act like a main verb. 'Have to' is used to express necessitis, obligations, certainty, etc. For instance:

I have to visit the dentist as soon as possible.

I had to redo everything because of his mistake.

Similarities

Certainty

We use 'should' and 'have to' to express certainty. Each of them expresses a different level of certainty. 'Have to' expresses a higher level of certainty than 'should.' Watch:

It should be Sara at the door.

It has to be Sara at the door.

Are They Interchangeable?

Compare the following examples:

I should visit my grandmother.

I have to visit my grandmother.

While by replacing them we still have a meaningful sentence, there is a difference in meaning.

The sentence with 'should' expresses something that is better to be done.
The sentence with 'have to' expresses something that is a must.

Therefore, 'should' and 'have to' are not interchangeable.

Differences

Talking about Necessities

When we want to express things we are obliged to do or need to do, we use 'have to.' Have a look:

I have to reply to his letter.

We had to take an oath in court.

Advice

We use 'should' to ask for and give advice. Advice is an opinion expressed about the right way to do something in a particular situation. For example:

When should I leave to take the early morning bus?

You should leave at 6 a.m.

Tip!

You may hear 'have to' in this context. It is correct to use it, but it is uncommon since 'have to' expresses a sense of order and might sound rude. Consequently, we recommend sticking to 'should.'

Negation

We can make sentences with 'should' and 'have to' negative. To do so, we simply add 'not' to them as illustrated below:

Should → Should not → Shouldn't
Have to → do/did/does not have to → don't/didn't/doesn't have to

Take a look at the following examples to see the negation process in action:

She should take the train. → She shouldn't take the train.

I had to wait for the bus. → I didn't have to wait for the bus.

Questions

We can use 'should' and 'have to' in interrogative forms:

Should

To create questions with 'should,' we simply invert it:

He should touch the dog. → Should he touch the dog?

Tom should write a guidebook. → Should Tom write a guidebook?

Have to

To make questions with 'have to,' we follow the pattern shown below:

Do/Did/Does + subject + have to + main verb + …?

For instance:

She has to go. → Does she have to attend the party?

I have to report what I saw. → Do I have to report what I saw?

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