〜はず: How to Say Something 'Should Be' / 'Supposed To' in Japanese

The judgement it makes

はず states an expectation you've reasoned your way to — you have a logical basis for believing something is the case, so you land on "should," "ought to," or "supposed to." Crucially, this isn't a hunch or a wish: it follows from facts you already hold. If the train always arrives at nine and it's now nine, the train should be here — that's はず. The stance is noticeably more confident than a plain guess, yet it stops short of asserting something as flat fact.

What it's built on

はず rests on two things: a reason in your head, and a plain form in front of it. The reason is what separates it from a bare guess — you use it when you can point to why. Grammatically it attaches to the plain form of the preceding word; the only fiddly parts are nouns and な-adjectives, which each demand a connector:

All plain-form tenses work too: 来たはず ("should have come"), 来ないはず ("shouldn't come"), 高くないはず ("shouldn't be expensive"). In its everyday use — plain はずだ — you simply state what you logically expect, with the reason usually sitting right beside it:

How sure it sounds

Japanese has a ladder of certainty, and はず sits high on it — backed by reason, but not absolute:

The key difference against its neighbours: でしょう and かもしれない report your guess about how likely something is, while はず says you have a reason to expect it. Use はず only when you can point to why — otherwise でしょう is more natural.

Turning it negative or past

Two twists reshape what はず claims. To say the opposite — that something is logically impossible — use はずがない (or the slightly softer はずはない). It's stronger than "I don't think so"; you're insisting there's no way it could be true.

Push はず into the past as はずだった and it describes a plan or expectation that didn't pan out. It leans on a contrast, so it often pairs with のに ("even though") or a "but" clause:

Watch-outs

The traps cluster around the connectors and the small particles that flip the meaning:

1. Forgetting の and な connectors. Nouns need の (学生のはず) and な-adjectives need な (静かなはず). Saying 学生はず or 静かはず is wrong — this is the exam's favourite trap.
2. Using はず with no basis. はず needs a reason. For a pure hunch about how likely something is, reach for かもしれない or でしょう instead.
3. Mixing up はずがない and はずだ. はずがない = "can't possibly be"; はずだ = "should be." Dropping or adding が flips the meaning entirely.
4. Using はずだった for things that did happen. はずだった signals an expectation that failed. If the plan worked out, just use the plain past.

The short version

• はず = a logical expectation: "should be," "ought to," "supposed to."
• Attaches to plain forms; nouns take の, な-adjectives take な.
• はずだ = I expect it's so; はずがない = it can't possibly be; はずだった = was supposed to (but didn't).
• More confident than でしょう or かもしれない because it rests on a reason.

Practice it