Grammar Point
word usually written using kana alone
uk 
auxiliary
aux 
はず

should (be), bound (to be), expected (to be), must (be)

Verb / い-Adjective + はず

Used to express a strong expectation or logical conclusion based on objective facts or circumstances. It indicates that the speaker believes something is certain to happen or be the case.

Verb (informal form)

When using a verb, use the dictionary form or the past tense (informal) before はず.

He should arrive soon.

い-Adjective

When using an い-adjective, use the dictionary form or the past tense (informal) before はず.

The movie should be interesting.

Note

はず cannot be used for things that are within the speaker's own control or for making a polite request. It also cannot be used for matters of simple future will; it must be based on some kind of evidence or logical reasoning.

な-Adjective / Noun + はず

Used with な-adjectives and nouns to express a logical expectation or a natural conclusion about a state or identity.

な-Adjective stem + な

Add な between the な-adjective stem and はず.

This room should be quiet.

Noun + の

Add の between the noun and はず.

Today should be a holiday.

Note

When negating はず, you can say はずがない (it is impossible that...) to express a very strong denial of an expectation.

Words: 
筈はず
弭はず
Radicals of radicals