Must vs Ought To: Difference and Comparison

‘Must’ and ‘Ought To’ are those words that are used to emphasize a sentence or make it sound important legally and formally, respectively. The words have a fragile difference in them.

Whenever a person wants to talk about the likelihood of an event, ‘Must’ and ‘Ought To’ can be used, but it depends on how much the speaker is confident about the event’s happening.

Key Takeaways

  1. “Must” indicate a mandatory action or obligation, whereas “ought to” suggests a strong recommendation or a desirable action.
  2. “Must” is used for rules or laws, while “ought to” is used for advice or social norms.
  3. The use of “must” implies a higher level of importance or urgency than ought to.

Must vs Ought To

The difference between ‘Must’ and ‘Ought To‘ is ‘Must’ represents when an obligation is external or duty, whereas ‘Ought To’ refers to a moral obligation. The emphasis is higher on ‘Must’ than ‘Ought To’. ‘Must’ is a modal verb. A modal verb is used to express modality. ‘Must’ can refer to past tense when it is used with the present perfect of the principal verb. ‘Must’ makes the sentence forceful. ‘Ought To’ is a semi-modal verb. The usage of ‘Ought To’ makes the sentence sound less powerful. ‘Must’ is more emphatic than ‘Ought To’. The word ‘Ought To’ is not forceful like ‘Must’.

Must vs Ought To

Language Quiz

Language quiz helps us to increase our language skills

1 / 10

Choose the word that is a synonym for "hasten":

2 / 10

Choose the word that means the opposite of "ascend":

3 / 10

What is the term for a word that is opposite in meaning to another word?

4 / 10

She’s wearing a ________ dress.

5 / 10

Choose the antonym for the word "big":

6 / 10

Fill in the blank. “Bad weather can ________ people’s ability to work.”

7 / 10

Who is the person in charge at a high school?

8 / 10

Which language has the largest number of speakers?

9 / 10

Choose the word that means the opposite of "discourage":

10 / 10

What is the term used to describe words that substitute for nouns?

Your score is


‘Must’ is used to express the need of the hour. It makes the sentence formal and legal. The emphasis is highest when ‘Must’ is used in the sentence. ‘Must’ is used when the event is likely to happen. ‘Must’ is a modal verb.

‘Must’ is used when the probability of happening if the event is higher. ‘Must’ is always about strength in the sentence.

‘Ought To’ is a type of modal verb. It refers to something which is morally correct in a particular situation. It is mostly used when seeking suggestions or recommending something to someone. It refers to objective truth. ‘Ought To’ does not have any past form.

It is rarely used in questions and negatives. ‘Ought To’ is the semi-modal verb. ‘Ought To’ is used when the event may or may not happen.

Comparison Table

Parameters Of ComparisonMustOught To
MeaningUsed to express necessityUsed to express moral obligation
Degree Of EmphasisHighestComparatively high
Likelihood of the eventHighMay or may not happen
TonePowerfulLess powerful
Kind of verbModal verbSemi-Modal verb

What is Must?

‘Must’ is used to express obligation, duty, or compulsion. ‘Must’ do not change its form with the tense, number, or person of the subject. 

Must’ is a helping verb. It emphasizes the importance or needs of something in a particular situation. ‘Must’ always signifies strong determination. The usage of ‘Must’ indicates that the speaker is certain that the subject will have executed the predicate.

It used to show a necessity.

An example is:

We must wake up early in the morning.

It is used to show logical probability, or probability is pretty high.

An example is:

That must be the postman.

It is used to hint at prohibition.

An example is:

One must not talk in the library.

It is used in an exclamatory sentence.

An example is:

You must be kidding!

It is used to recommend something or advise something strongly.

Whenever there is a need for emphasis, and the level of emphasis is high, ‘Must’ is always used in the sentence.

It is used in directive requirements.

An example is:

The door handle must be rotated fully.

It is used to make an imperative sentence.

An example is:

You must arrive in class on time.

must 1

What is Ought To?

‘Ought To’ differs from other auxiliary verbs, followed by a to-infinitive. ‘Ought to’ point present and future time. It can refer to a past time when it is followed by the perfect infinitive (have + past participle). 

It indicates when it is essential and proper to do, referred to by the verb succeeding it.

An example is:

The students ought to be punctual at school.

It is used to indicate the probability of something that may happen.

An example is:

The seminar ought to increase awareness.

It is used to discuss those things which are prolonged for or ideal.

An example is:

The government ought to make better traffic rules.

It is used to express duty.

An example is:

She ought to follow traffic rules.

Main Differences Between Must and Ought To

  1. ‘Must’ refers to the sentence’s legal terminology, whereas ‘The speaker uses Ought To’ to sound formal.
  2. The degree of emphasis is higher in ‘Must’ instead of ‘Ought To’.
  3. ‘Ought To’ is used when discussing moral duties, but ‘Must’ is used to express necessity.
  4. ‘Must’ is used in the sentence when the probability of happening is higher, whereas ‘Ought To’ is used when the probability of happening is not sure.
  5. ‘Must’ and ‘Ought To’ are both called obligations, but ‘Must’ is for external obligation, and ‘Ought To’ refers to moral obligation.
Difference Between Must and Ought To

Last Updated : 11 June, 2023

dot 1
One request?

I’ve put so much effort writing this blog post to provide value to you. It’ll be very helpful for me, if you consider sharing it on social media or with your friends/family. SHARING IS ♥️

Leave a Comment

Your email address will not be published. Required fields are marked *

Want to save this article for later? Click the heart in the bottom right corner to save to your own articles box!