Expectation Based on Evidence
はず expresses what you expect because you have a reason — a schedule, a promise, common knowledge. It is not a wish and not a duty.
- 彼は三時に来るはずです。(He should be here at three — that's what we arranged.)
Attaching It
はず behaves as a noun, so things connect to it the way they connect to any noun:
| Type | Form |
|---|---|
| Verb | 来るはず |
| い-adjective | 安いはず |
| な-adjective | 暇なはず |
| Noun | 休みのはず |
The な and の are the ones people forget.
はず vs べき — A Real Trap
English "should" covers both, Japanese does not:
| Pattern | Meaning |
|---|---|
| 来るはずです | He should be here (I expect it) |
| 来るべきです | He ought to come (it's his duty) |
はず is prediction. べき is obligation. Mixing them up changes a comment about a train timetable into a moral judgement.
はずがない — Denial
Not simply "shouldn't" — it means "there's no way":
- 彼が嘘をつくはずがない。(There's no way he'd lie.)
This is stronger than a plain negative. It rejects the possibility outright.
はずだった — It Didn't Happen
The past form usually implies the expectation was not met:
- 今日来るはずだったのに、来なかった。(He was supposed to come today, but he didn't.)
Where はず Sits Among the Guesses
| Pattern | Confidence |
|---|---|
| かもしれない | might |
| でしょう | probably |
| はず | should be — I have a reason |
| に違いない | must be — near certain |