はずだ

The expression はずだ is used to convey a strong expectation or belief that something should be the case, based on reasoning, evidence, or prior knowledge. It translates to "it should be," "it must be," "it is expected to," or "it is supposed to." Unlike simple guessing, はずだ implies that the speaker has a logical basis for their belief.

Structure

はずだ attaches to the plain form of verbs, adjectives, and nouns:

• Verb (plain form) + はずだ: くる来る → 来るはずだ - い-adjective + はずだ: やすい安い → 安いはずだ - な-adjective + な + はずだ: しずか静か → 静かなはずだ - Noun + の + はずだ: やすみ休み → 休みのはずだ

Expressing expectation based on reasoning

When you have good reason to believe something is true, はずだ communicates that confidence.

The speaker is not just guessing – they have a basis (e.g., a schedule, prior experience, or information from someone else).

Past tense

To express that something should have been the case in the past, use the past plain form before はずだ.

Negative form: はずがない

To strongly deny that something could be true – "there's no way that…" – use はずがない instead of はずだ.

This is much stronger than simply negating the verb before はずだ. Compare:

• こない来ないはずだ – "He is expected not to come." (neutral expectation)
• きたる来るはずがない – "There's no way he will come." (strong denial)

Negating the expectation itself: はずではなかった

When something happens contrary to expectation, use はずではなかった to express "it wasn't supposed to be this way."

はずだ vs. べきだ

Be careful not to confuse はずだ with べきだ. While はずだ expresses expectation based on logic ("it should be the case"), べきだ expresses obligation or moral judgment ("one ought to do"). They are quite different in meaning despite both sometimes being translated as "should" in English.