〜はず: How to Say Something 'Should Be' / 'Supposed To' in Japanese
What it means
はず expresses an expectation grounded in reason — you have a logical basis for believing something is the case. It's usually translated "should," "ought to," or "supposed to." Crucially, this isn't a hunch or a wish; it follows from facts you already know. If the train always arrives at nine and it's now nine, the train should be here — that's はず. It's noticeably more confident than a simple guess but stops short of stating something as flat fact.
先生はもう着いているはずだ。
せんせいは もう ついて いる はずだ。
The teacher should already have arrived.
Based on reason: she left an hour ago.
ヤッタンは日本語が話せるはずです。
ヤッタンは にほんごが はなせる はずです。
Yattan should be able to speak Japanese.
はずです is the polite version.
この店は今日休みのはずだ。
この みせは きょう やすみの はずだ。
This shop is supposed to be closed today.
Noun (休み) takes の before はず.
How to form it
はず attaches to the plain form of the word in front of it. The only tricky parts are nouns and な-adjectives, which need a connector:
| Word type | Connection | Example |
|---|---|---|
| Verb (plain) | verb + はず | 来るはず (should come) |
| い-adjective | adj + はず | 高いはず (should be expensive) |
| な-adjective | adj + な + はず | 静かなはず (should be quiet) |
| Noun | noun + の + はず | 学生のはず (should be a student) |
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").
〜はずだ — "I expect it's so"
This is the everyday use: you state what you logically expect to be true.
モチは鍵を持っているから、入れるはずだ。
モチは かぎを もって いるから、はいれる はずだ。
Mochi has the key, so he should be able to get in.
The reason (持っている) makes はず natural.
この問題は簡単なはずだったのに、難しかった。
この もんだいは かんたんな はずだったのに、むずかしかった。
This problem was supposed to be easy, but it was hard.
簡単 is a な-adjective, so 簡単なはず.
〜はずがない / はずはない — "it can't possibly be"
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 just "I don't think so"; you're saying there's no way it could be true.
ヤッタンがそんなことを言うはずがない。
ヤッタンが そんな ことを いう はずが ない。
There's no way Yattan would say something like that.
あんなに勉強したのに、不合格のはずがない。
あんなに べんきょうしたのに、ふごうかくの はずが ない。
After studying that much, there's no way she failed.
Noun (不合格) + の + はずがない.
〜はずだった — "was supposed to (but…)"
Put はず into the past as はずだった to describe a plan or expectation that didn't pan out. It often pairs with のに ("even though") or a contrasting clause.
ヤッタンの弟は今日来るはずだったが、来なかった。
ヤッタンの おとうとは きょう くる はずだったが、こなかった。
Yattan's little brother was supposed to come today, but he didn't.
電車は五時に着くはずだったのに、遅れている。
でんしゃは ごじに つく はずだったのに、おくれて いる。
The train was supposed to arrive at five, but it's late.
How sure is はず? Comparing the levels
Japanese has a ladder of certainty, and はず sits high on it — backed by reason, but not absolute:
| Form | Core idea | Example |
|---|---|---|
| かもしれない | maybe (a real possibility) | 来るかもしれない = (he) might come |
| でしょう | probably (a confident guess) | 来るでしょう = (he) will probably come |
| はず | should — logical expectation from evidence | 来るはずだ = (he) should come |
| (plain statement) | fact | 来る = (he) is coming |
The key difference: 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.
Common mistakes
- 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.
- 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.
- 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.
- 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.
Quick recap
- 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.
Your turn
Choose the correct はず form (はずだ / はずがない / はずだった) and connector.
Start the 5-question drill →Frequently asked questions
What's the difference between はず and でしょう?
はず means something should be true because you have a logical reason for it (来るはずだ — he said he'd come, so he should). でしょう is just a confident guess about likelihood (来るでしょう — he'll probably come). Use はず when you can point to evidence.
How do nouns and な-adjectives connect to はず?
Nouns add の: 学生のはず ('should be a student'). な-adjectives add な: 静かなはず ('should be quiet'). Verbs and い-adjectives attach directly: 来るはず, 高いはず.
What does はずがない mean?
It means 'there's no way' or 'it can't possibly be': そんなはずがない ('that can't be right'). It's the logical opposite of はずだ — you're saying something is impossible based on reason.
When do I use はずだった?
Use はずだった for a plan or expectation that didn't come true: 来るはずだったが、来なかった ('he was supposed to come, but didn't'). It usually pairs with a contrasting clause like のに or が.