Must vs Should

When to use each in English, with meaning, register, and examples.

Must

High-frequency chunk A1

Should

Top 1,000 (very common) A1

	Must	Should
Pronunciation	🇬🇧 /["/məst//mʌst/","/ˈmʌsnt/"]/ 🇺🇸 /["/məst//mʌst/","/ˈmʌsnt/"]/	🇬🇧 /["/ʃəd//ʃʊd/","/ˈʃʊdnt/"]/ 🇺🇸 /["/ʃəd//ʃʊd/","/ˈʃʊdnt/"]/
Meaning	Something that is necessary or very important.	used to tell someone what is the right thing to do
Example	You must finish your homework before playing outside.	You should study for the exam to do well.
Register	Neutral	Neutral
How common	High-frequency chunk	Top 1,000 (very common)
CEFR level	A1	A1
Collocations	must see, must do, must have, must remember	should do, should have, should not, should consider, should remember
Antonyms	can, may, might	must not, shall not
Common mistakes	Using 'must' in situations where 'have to' is more suitable., Confusing 'must' with 'might' or 'may', which imply possibility instead of necessity., Using 'must' with the gerund form instead of the base form of the verb.	'Should' is often confused with 'must,' leading to weaker advice than intended., Forget to follow 'should' with the base form of the verb, e.g., saying 'should goes' instead of 'should go.', Using 'should' for past events instead of 'should have.'
Usage notes	Use 'must' when giving strong advice or making strong recommendations. Avoid using it in casual conversations where 'should' might be more appropriate.	Use 'should' for advice, suggestions, or expectations. It's appropriate in both spoken and written English, but avoid it in very formal contexts where 'ought to' might be preferred.

See it in real clips

I must have drank me about 15 Dr Peppers.

A Knight Of The Seven Kingdoms › S1 E1

Must you mock me?

Game Of Thrones › S1 E1

You must be Robb.

I must have drank me about 15 Dr Peppers.

A Knight Of The Seven Kingdoms › S1 E1

Must you mock me?

Must

Frequently asked questions: Must vs Should

What's the difference between Must and Should?

Must: Something that is necessary or very important. Should: used to tell someone what is the right thing to do

Are Must and Should the same CEFR level?

Must: A1, Should: A1 on the CEFR scale.

Can you show an example of each?

Must: You must finish your homework before playing outside. Should: You should study for the exam to do well.

Can I use Must and Should interchangeably?

Not always. Must and Should are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.