～はず: How to Express Logical Expectation in Japanese

～はず expresses logical expectation in Japanese: what should be the case based on evidence, schedules, or reasoning, rather than a bare guess.¹ For N4 learners, it separates predictive "should" from duty "should," two ideas English collapses into one word.

Overview

はず is a dependent (formal) noun: a noun that cannot stand alone and always attaches to a preceding clause.¹ It means the speaker is quite sure a proposition is true, will be true, or was true, but cannot confirm it directly.¹

The dictionary sense captures the same idea: 「当然そうなるべき道理であることを示す」, "shows that something follows naturally and logically," and that the speaker holds that conviction.²

What はず expresses

はず reports a confident inference: "it should be the case," "it ought to be so," "I expect that." It is not a wish or a command. The speaker reads the situation and concludes what must follow.

彼かれは今日きょう来くるはずです。¹
"He should be coming today."

Because はず is grammatically a noun, it takes the copula (はずだ / はずです). It also connects to the words before it exactly as any noun-modifying clause would.¹ That fact drives every connection rule in the next section.

もうすぐタクシーが来くるはずだ。³
"The taxi should arrive soon."

The core idea: expectation with a basis

The defining feature of はず is that the expectation rests on an objective or logical ground: a schedule, a known fact, evidence, or a chain of reasoning.⁴ Dictionaries gloss the underlying idea as 道理・理屈, "logic and reason."⁴

表おもてに出でているなら、夏なつだから暑あついはずだ。³
"If you are outside, it should be hot, since it is summer."

This grounding is why はず ranks high on the certainty scale. In the analysis of epistemic modality (認識的モダリティ, the grammar of how sure a speaker is), はず expresses a high 確信度, or degree of conviction. It sits above subjective conjecture forms.⁵⁶

この地図ちずを見みれば分わかるはずだ。⁷
"If you look at this map, you should be able to figure it out."

The basis is what makes it はず, not the strength

A pure hunch with no pointable basis is not はず territory. When you only have a feeling, use the subjective-conjecture forms だろう (probably) and かもしれない (it may be). はず claims a ground the speaker can name.⁶

Form and connection rules

Since はず behaves as a noun, the word in front of it must be in a noun-modifying (attributive) form.¹ That one principle generates the table below. Verbs and い-adjectives attach in their plain form, while な-adjectives and nouns need their usual linking elements (な, の), just as they would before any other noun.

Connecting はず to verbs, adjectives, and nouns

Preceding word	Connection	Affirmative example	Past-state example
Verb	plain form + はず	来るはず ("should come")	来たはず ("should have come")
い-adjective	plain form + はず	高いはず ("should be expensive")	高かったはず ("should have been expensive")
な-adjective	stem + な + はず	静かなはず ("should be quiet")	静かだったはず ("should have been quiet")
Noun	noun + の + はず	学生のはず ("should be a student")	学生だったはず ("should have been a student")

Connection rules per DBJG and Genki II.¹⁸

The four patterns share one shape: an attributive form feeds into the noun はず. In the tree below, they all converge on the same node.

A な-adjective keeps its な link before はず, and a noun keeps its の link.

明日あしたの試験しけんは簡単かんたんなはずだ。³
"Tomorrow's exam should be easy."

試験しけんは明日あしたのはずだ。³
"The exam should be tomorrow."

A past-tense verb before はず (たはず) yields "should have already happened": the speaker expects the event has occurred by now.⁸

彼かれはもう着ついたはずだ。⁸
"He should have arrived already."

To make the predicate negative, negate the verb, adjective, or noun before はず. はず itself stays intact: 来ないはず ("should not come"), 高くないはず ("should not be expensive"), 学生ではないはず ("should not be a student").¹ This differs from はずがない, covered later.

彼女かのじょは今いま、家いえにいないはずだ。³
"She shouldn't be home right now."

はずだ, はずです, and casual drops

はずだ is the plain-style form, and はずです is the polite-style form. Both are register-neutral and fully acceptable in writing and speech.¹²

In casual speech, the copula can be dropped, leaving a bare はず, or はず？ with rising intonation as a tentative confirmation. はずだと思う ("I think it should be...") softens the assertion further.³

「コンサートは6時ろくじに始はじまるんだっけ？」「そのはずだけど。」³
"The concert starts at six, right?" "It should, yeah."

そのはずだ is a fixed reply that confirms a proposition just raised. その stands in for the noun-modifying clause.³

駅えきで待まち合あわせのはずだよね？³
"We're supposed to meet at the station, right?"

The three core patterns

はずだ, はずがない, and はずだった form one expectation system: a baseline reading, its logical denial, and its past form. They are easier to read together than as unrelated grammar points.

～はずだ: it logically should be

はずだ is the baseline pattern: a confident inference that a proposition is or will be true, grounded in evidence, schedules, or deduction.¹² Dictionaries repeatedly note two everyday uses: deduction from a fact (当然そうなることの意, "it naturally turns out this way") and a scheduled or planned event (予定を表す, "is supposed to ...").⁷

彼かれは日本にほんに5年ごねん住すんでいたから、日本語にほんごが上手じょうずなはずだ。¹
"He lived in Japan for five years, so his Japanese should be good."

The scheduled-event reading is the one learners meet first, since it maps cleanly onto "is supposed to."

会議かいぎは5時ごじに終おわるはずだ。⁷
"The meeting is supposed to end at five."

荷物にもつは明日あした届とどくはずです。³
"The package should arrive tomorrow."

～はずがない / はずはない: there's no way

はずがない, and the variant はずはない, deny the possibility of a proposition: there is no basis on which it could be true, so "there's no way" or "it's impossible."¹ Structurally, が or は marks はず, and ない negates the existence of any such expectation.

彼女かのじょがあんな人ひとを好すきになるはずがない。³
"There's no way she'd fall for a man like that."

A polite-form variant はずがありません / はずはありません exists for formal speech.³

そんなやり方かたでうまくいくはずがありません。³
"There's no way it'll work out doing it like that."

The two are largely interchangeable. はずがない, with が, is the more common and neutral choice. はずはない simply substitutes the topic particle は for the subject particle が, and reads the same way in most contexts.³

こんな簡単かんたんな問題もんだい、彼かれが間違まちがえるはずはない。³
"A problem this easy? There's no way he gets it wrong."

～はずだった: was supposed to but didn't

はずだった puts はず itself into the past and typically carries a counterfactual implication: the speaker expected the event, but it did not happen as expected. It often carries surprise, disappointment, or regret.¹ The reading is "was supposed to ... but didn't."

彼かれとは昨日きのう会あうはずだった。³
"I was supposed to meet him yesterday."

It frequently co-occurs with のに ("...but / even though"), which makes the unmet-expectation reading explicit.³

全すべてうまくいくはずだったのに。³
"Everything was supposed to go well..."

たはず and はずだった are not the same past

たはず (verb past + はず) means "should have already happened," and the speaker still believes it occurred: 着いたはず, "he should have arrived." はずだった (はず + past copula) frames the expectation itself in the past and often signals that it went unfulfilled. Keep the two apart.¹⁸

9時くじの電車でんしゃに乗のるはずだったが、寝坊ねぼうした。³
"I was supposed to catch the nine o'clock train, but I overslept."

Nuance and usage contexts

はず sits near several forms that learners often confuse with it. The sections below draw the boundaries: against duty (べき), against subjective guesses (だろう, かもしれない), against reasoned conclusions (わけ), and against itself when negation enters.

はず vs べき: expectation, not duty

はず states what logically should be the case (expectation and inference). べき states what one ought to do (obligation, moral or social duty).⁹ English "should" covers both senses, which is the root of the N4-level confusion.

べき attaches to a verb in dictionary form (するべき / すべき) and expresses the speaker's judgment that an action is required. It carries a prescriptive, sometimes know-it-all tone that はず never has.⁹ The two are not interchangeable.

約束やくそくしたのだから、彼かれは来くるはずだ。¹
"He promised, so he should be coming."

約束やくそくしたのだから、彼かれは来くるべきだ。⁹
"He promised, so he ought to come."

The first sentence predicts his behaviour; the second judges it. Swapping はず for べき changes the meaning, not just the politeness.

はず on the certainty scale

In the analysis of epistemic modality, Japanese conjecture forms are ranked by 確信度, or degree of certainty. From lower to higher conviction, the standard ordering is かもしれない (it may be) < だろう / でしょう (probably) < はず / にちがいない (it surely is / it must be).⁵⁶ These band labels are the conventional ordering used in the grammar literature, not an official ranking.

The axis that separates はず from だろう and かもしれない is basis, not only strength. はず requires a pointable objective ground, while だろう and かもしれない are subjective conjecture forms that need no such ground.⁵⁶

明日あしたは雨あめが降ふるかもしれない。⁶
"It might rain tomorrow."

明日あしたは雨あめが降ふるだろう。⁶
"It will probably rain tomorrow."

The はず version differs from both by naming its evidence inside the sentence.

予報よほうが雨あめだったから、明日あしたは雨あめが降ふるはずだ。⁵
"The forecast said rain, so it should rain tomorrow."

にちがいない sits near はず in certainty, but it reads as the speaker's strong subjective conviction. はず foregrounds the objective and logical grounding. The two are close but not identical on the basis axis.⁶

はず vs わけ: expectation vs conclusion

はず is a not-yet-confirmed expectation the speaker projects forward ("it should be / I expect").¹ わけ(だ) is a conclusion the speaker draws to explain something already known or observed ("so that's why / it follows that").¹ The two face opposite directions. はず looks ahead to what should hold, while わけだ looks back to explain a known fact.

彼かれはもう着ついているはずだ。¹
"He should have arrived by now."

わけだ is usually taught at a more advanced level (commonly N3) and is the standard contrast partner for はず: expectation versus reasoned explanation.⁹

道みちが混こんでいたのか。遅おくれるわけだ。⁹
"Oh, the roads were jammed. That's why he's late."

来ないはず vs 来るはずがない

These are the two ways negation interacts with はず, and they are not synonyms.¹ One negates the content of the expectation. The other denies the expectation itself.

• 来ないはず negates the predicate and keeps はず: "I expect that he will not come." The speaker holds a positive expectation whose content is negative.
• 来るはずがない keeps the predicate positive and denies the expectation: "there's no way he comes." The speaker rules the possibility out.

来るはずがない is much stronger: it denies that the proposition could be true at all. 来ないはず merely reports the speaker's expectation that it will not occur.¹³

彼かれは忙いそがしいから、来こないはずだ。¹
"He's busy, so I don't expect him to come."

あんなに遠とおいんだから、彼かれが歩あるいて来くるはずがない。³
"It's that far away, so there's no way he comes on foot."

The two negation slots can also combine. 知らないはずがない negates both the predicate and the expectation, which cancels out into a strong positive: "there's no way he doesn't know," that is, he must know.³

マギーがそのことを知しらないはずがない。³
"There's no way Maggie doesn't know about that."

Good to know

筈 is the nock of an arrow

The noun 筈 originally names archery hardware: 矢筈 (やはず), the notched end of an arrow that catches the bowstring, and 弓筈 (ゆはず), the notches at the ends of a bow where the string is seated.⁴¹⁰ The grammatical sense developed from this in the late medieval period. The arrow's nock is built to fit the bowstring exactly: 「矢の筈は弓の弦と当然合致する」, "the arrow's nock naturally matches the bowstring." From there, 筈 came to mean "what naturally and logically should be so."⁷¹¹

This is the clearest hook for the objective-basis nuance. Like a nock seating on a string, a はず claim is one where things fit as they logically must.¹¹

Using はず for a pure hunch with no basis

はず requires an objective or logical ground the speaker can point to: a forecast, a schedule, or a fact. With only a vague feeling (なんとなく, "somehow"), the form なんとなく、明日は雨が降るはずだ sounds off, because it claims a basis that is not there. Use a conjecture form instead.⁵⁶

なんとなく、明日あしたは雨あめが降ふる気きがする。⁶
"I somehow have a feeling it'll rain tomorrow."

Confusing "expect not to" with "no way"

To say "I expect he isn't the culprit," negate the predicate: 彼は犯人ではないはずだ. To say "there's no way he's the culprit," deny the expectation: 彼が犯人のはずがない. Using 彼が犯人のはずがない for the first meaning is wrong, because はずがない rules the possibility out rather than reporting a negative expectation. Learners routinely conflate the two, but they differ in both strength and meaning.¹³

彼かれは犯人はんにんではないはずだ。¹
"I expect he isn't the culprit."

Reaching for はず when "should" means duty

When English "should" means obligation or advice, はず is the wrong choice. 君は先生に謝るはずだ wrongly states a prediction about the listener's behaviour when the intended meaning is "you should apologize." Duty is carried by べき(だ) or 方がいい, not はず.⁹

君きみは先生せんせいに謝あやまるべきだ。⁹
"You should apologize to the teacher."

Register: neutral form, speech-only drops

はずだ and はずです are both fine in writing and in formal speech.² The bare-はず drop and the はず？ rising-intonation confirmation are conversational. In formal writing, keep the copula, as in はずだ or はずである.³

See also

• ～つもり: How to State a Firm Intention in Japanese (and the つもりだった Trap)
• Inferential Suffixes in Japanese: ～そう, ～よう, ～らしい, ～みたい Compared
• ～なければならない / ～なきゃ: How to Say "I Have To" or "Must" in Japanese
• The わけ-Family Negatives: ～わけではない, ～わけがない, ～わけにはいかない

References

Footnotes

1. Makino, Seiichi, and Michio Tsutsui. A Dictionary of Basic Japanese Grammar. The Japan Times, 1986, entry はず, p. 133. (Modified Hepburn used in this source.) ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³

2. 『デジタル大辞泉』小学館. Entry 筈 (はず), via kotobank. https://kotobank.jp/word/%E7%AD%88-601333 ↩ ↩² ↩³ ↩⁴

3. Maggie Sensei. "How to use はず (= hazu)." https://maggiesensei.com/2012/11/14/request-lesson-how-and-when-to-use-はずhazu/ (limitation: language-learning blog; used only to verify naturalness of example sentences, not for grammatical rules.) ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴ ↩²⁵

4. 『精選版 日本国語大辞典』小学館. Entry 筈・弭 (はず), via kotobank. https://kotobank.jp/word/%E7%AD%88%E3%83%BB%E5%BC%AD-358452 ↩ ↩² ↩³

5. 国立国語研究所 (NINJAL). 仁田義雄ほか『日本語の文法 4 モダリティ』岩波書店, 2003. (Epistemic modality / 認識的モダリティ framework; 確信度 certainty-degree scale.) ↩ ↩² ↩³ ↩⁴ ↩⁵

6. 庵功雄『新しい日本語学入門 第2版』スリーエーネットワーク, 2012. (対事的モダリティ classification placing かもしれない / だろう / にちがいない / はず on a certainty scale.) ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹

7. 『大辞林』三省堂. Entry はず (筈). (Archery senses 弓筈 / 矢筈 and the figurative sense; etymology note 矢の筈は弓の弦と当然合致するということから.) ↩ ↩² ↩³ ↩⁴

8. Banno, Eri, et al. Genki II: An Integrated Course in Elementary Japanese. 3rd ed., The Japan Times, 2020, Lesson 17 (はずです), pp. 142, 168, 172. ↩ ↩² ↩³ ↩⁴

9. Makino, Seiichi, and Michio Tsutsui. A Dictionary of Intermediate Japanese Grammar. The Japan Times, 1995, entry べき(だ). (Obligation auxiliary; contrast with expectation.) ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

10. 『デジタル大辞泉』小学館. Entry 矢筈 (やはず), via kotobank. https://kotobank.jp/word/%E7%9F%A2%E7%AD%88-143914 ↩

11. 語源由来辞典. 「筈／はず」. https://gogen-yurai.jp/hazu/ ↩ ↩²