～はずだ
should / is supposed to
～はずだ follows a plain-form clause and expresses a confident expectation based on reasoning: given what the speaker knows, things should be that way. It does not state a fact, it states a well-founded conclusion.
English equivalents are “should” or “is supposed to” in the sense of expectation. Be careful: unlike ～べきだ, which is “should” as in duty (“you should apologize”), ～はずだ is “should” as in prediction (“he should arrive soon”). The negative ～はずがない (“there is no way that...”) is a separate pattern.
1. Expectation about the present or future
The speaker has grounds like a schedule, a promise, common knowledge and concludes that something is or will be the case.
彼は来るはずだ。
“He should be coming.”
- 彼（かれ）= he
- は = topic marker
- 来る（くる）= to come
- はずだ = should / is expected to
2. Expectation about the past
With a past-tense clause, ～はずだ means something should have happened by now, as far as the speaker can reason.
彼女はもう家に着いたはずです。
“She should have arrived home by now.”
- 彼女（かのじょ）= she
- もう = already, by now
- 家（いえ）= home
- に = destination marker
- 着いた（ついた）= arrived
- はずです = should have (polite expectation)
How to form it
Plain form + はずだ (nouns take のはずだ, な-adjectives take なはずだ)
- 来る（くる）= to come → 来るはずだ（くるはずだ）= should come
- 終わる（おわる）= to end → 終わったはずだ（おわったはずだ）= should have ended
- 学生（がくせい）= student → 学生のはずだ（がくせいのはずだ）= should be a student
Key idea
～はずだ says: “based on what I know, this is what I expect to be true.” If the evidence points one way, use はずだ; if you are telling someone their duty, that is べきだ.
Built on the same stem
Updated .