Expectation はず in Japanese

In Brief

Use はず when the facts, a plan, or your knowledge lead you to expect something: 田中さんは来るはずです means “Ms. Tanaka should come” because you have a reason to think so. Put a plain form before はず, but remember な-adjective + なはず and noun + のはず. ないはず means “is expected not to,” while はずがない means “cannot possibly.”

Overview

はず presents a conclusion that the speaker considers reasonable. Perhaps the timetable says the shop opens at nine, a friend promised to attend, or a calculation gives a particular result. English often translates it as “should,” “ought to be,” “is supposed to,” or “must be,” but the important idea is not the English word: it is the reasoning behind the expectation.

This B1 pattern builds on the Japanese plain form (the non-ます form used before many grammar patterns). It works with verbs, adjectives, and nouns. The sentence can remain polite because politeness appears at the end: 来るはずです, not 来ますはずです.

Unlike an obligation, はず does not normally tell someone what they ought to do. 来るはずです predicts or expects that someone will come; it does not mean “You should come” as advice. This difference prevents many mistakes caused by the wide range of English should.

How It Works

Basic structure

The word before はず describes the situation that is expected. はず then behaves much like a noun, so the ending can be だ, polite です, a negative form, or a past form.

Word type	Pattern	Example	Meaning
Verb	plain form + はずだ	来るはずだ	should come
い-adjective	plain form + はずだ	安いはずだ	should be inexpensive
な-adjective	stem + な + はずだ	静かなはずだ	should be quiet
Noun	noun + の + はずだ	休みのはずだ	should be a day off / should be closed

For verbs, any plain tense or polarity can come before はず:

Form before はず	Example	Core meaning
Non-past affirmative	行くはずです	is expected to go
Non-past negative	行かないはずです	is expected not to go
Past affirmative	行ったはずです	is expected to have gone
Past negative	行かなかったはずです	is expected not to have gone
Progressive/result state	着いているはずです	should have arrived / should be there

Japanese non-past forms can refer to the future, so 明日来るはずです naturally means “They should come tomorrow.” A past form places the expected event before the reference time: もう出発したはずです means “They should have left already.”

Choosing the sentence ending

• はずだ is plain and direct.
• はずです is polite and common in conversation.
• はずだった / はずでした means that something was expected or planned. Context often implies that reality differed.
• はずではない denies that something is the expected case, though other negative patterns are often more natural for a specific meaning.

The evidence does not need to be stated, but it should be available from context. You can make it explicit with phrases such as 予定では (“according to the schedule”), 地図によると (“according to the map”), or a reason ending in から (“because”).

Two very different negatives

The position of the negative changes the meaning.

Japanese	English	Note
山田さんは今日は来ないはずです。	Mr. Yamada is not expected to come today.	The expected proposition itself is negative.
山田さんが来るはずがありません。	There is no way Mr. Yamada will come.	The possibility of the expectation is rejected.
山田さんが知らないはずはありません。	There is no way Mr. Yamada does not know.	A negative proposition plus はずはない produces “he must know.”

In short:

• X ないはずだ: “I expect that X will not happen.”
• X はずがない / はずはない: “There is no possibility that X is true.”
• X ないはずがない: “It cannot be that X is not true,” often equivalent to “X must be true.”

The last pattern contains two negatives and can take time to process. For example, まだ届いていないはずがありません literally rejects the possibility that it has not arrived yet: “It can’t be that it hasn’t arrived yet,” so the speaker strongly concludes that it has arrived.

Examples in Context

Japanese	English	Note
彼は来るはずです。	He should come.	Based on an expectation or known plan.
電車は十時に着くはずです。	The train is supposed to arrive at ten.	A timetable supports the conclusion.
この薬を飲めば、すぐ楽になるはずです。	If you take this medicine, you should soon feel better.	The condition supplies the reasoning.
駅の近くですから、歩いて十分ぐらいのはずです。	Since it is near the station, it should be about a ten-minute walk.	A reason is stated with から.
試験は簡単なはずです。	The exam should be easy.	な-adjective: 簡単なはず.
今日は祝日なので、銀行は休みのはずです。	Since today is a public holiday, the bank should be closed.	Noun: 休みのはず.
鍵は机の上にあるはずです。	The key should be on the desk.	Expected location.
彼女はもう家に着いているはずです。	She should be home by now.	An expected resulting state.
メールは昨日届いたはずです。	The email should have arrived yesterday.	Past event inferred from the facts.
佐藤さんは肉を食べないはずです。	Ms. Sato is not supposed to eat meat.	The expected fact is negative.
この時間なら、道は混んでいないはずです。	At this hour, the roads should not be busy.	Negative expectation.
そんなはずがない。	That can’t be right.	A common strong reaction.
彼が約束を忘れるはずはありません。	There is no way he would forget his promise.	はずはありません strongly rejects the idea.
知らないはずはありません。	There is no way you do not know.	Context identifies who knows.
会議は三時に始まるはずでした。	The meeting was supposed to start at three.	Often suggests that it did not start then.

Common Mistakes

Attaching はず to a polite verb

• Wrong: 彼は来ますはずです。
• Right: 彼は来るはずです。
• Why: Grammar expressions such as はず attach to the plain form. Put politeness on the final です.

Forgetting な after a な-adjective

• Wrong: この部屋は静かのはずです。
• Right: この部屋は静かなはずです。
• Why: A な-adjective uses な before はず. The noun pattern uses の, as in 休みのはずです.

Using はず for advice or duty

• Wrong for “You should study more”: もっと勉強するはずです。
• Right: もっと勉強したほうがいいです。
• Why: はず reports an expectation: the incorrect sentence sounds like “You are expected to study more” based on known circumstances. For advice, 〜たほうがいい is usually appropriate; for moral duty, べきだ may fit.

Confusing ないはず with はずがない

• Wrong for “He can’t come”: 彼は来ないはずです。
• Right: 彼が来るはずがありません。
• Why: 来ないはず merely says you expect him not to come. 来るはずがない rejects the possibility more forcefully.

Using はず for a guess with no basis

• Unnatural in the intended meaning: たぶん田中さんは家にいるはずです。 (“Maybe, with no particular reason, Tanaka is home.”)
• Better: たぶん田中さんは家にいると思います。
• Why: はず normally signals a reasoned conclusion. For an ordinary uncertain opinion, と思う is safer. たぶん and はず can occur together when there is evidence but the speaker still softens the conclusion; they are not grammatically incompatible.

Usage Notes

Evidence, confidence, and reality

はず expresses what follows from the speaker’s information, not guaranteed truth. Plans change, memories fail, and evidence can be incomplete. もう着いたはずです can therefore be followed by でも、まだ連絡がありません: “They should have arrived, but I have not heard from them yet.”

Because はず points to an expected reality, challenging another person with そんなはずはない can sound forceful: “That cannot be.” In a polite disagreement, give your reason or soften the statement: 私の記憶では、そうではないはずですが… (“As I remember it, I don’t think that should be the case, but…”).

“Supposed to” is not always はず

English be supposed to has several meanings. はず fits an expectation arising from a schedule, arrangement, or information: バスは六時に出るはずです. If “supposed to” means a rule or requirement, ことになっている may be better: ここでは靴を脱ぐことになっています (“You are required to remove your shoes here”). If it means advice, choose a form such as ほうがいい.

はずがない and はずはない

Both forms strongly reject a possibility. が presents the expected possibility as nonexistent; は often adds contrast or emphasis. In many everyday sentences their practical meanings overlap. Polite forms are はずがありません and はずはありません. The compact わけがない can also mean “there is no way,” but it belongs to a broader family built around explanation and circumstances; do not treat it as a word-for-word replacement in every sentence.

Beyond the Basics / Advanced Use

An expectation that was not fulfilled

〜はずだった looks back at an expectation or arrangement: 昨日届くはずだった (“It was supposed to arrive yesterday”). It often carries the implication “but it did not,” though the grammar itself does not logically guarantee failure. The following context settles the issue:

Japanese	English	Note
荷物は昨日届くはずだったが、まだ来ていない。	The package was supposed to arrive yesterday, but it still has not come.	Clearly unfulfilled.
昨日届くはずだった荷物を、今朝確認した。	This morning I checked the package that was due to arrive yesterday.	The sentence alone does not explicitly say whether it arrived.

はずなのに: expectation versus reality

Adding のに (“although/even though”) makes the mismatch explicit: 簡単なはずなのに、全然できませんでした means “It was supposed to be easy, but I could not do it at all.” Before のに, はず links with な, giving はずなのに. This pattern often communicates surprise, frustration, or disappointment.

はずだ as a realization

Sometimes はず marks a conclusion that explains what you have observed:

道がぬれている。雨が降ったはずだ。
“The road is wet. It must have rained.”

In natural conversation, わけだ may instead express “no wonder / that explains it” when the speaker has just learned the explanation. はず keeps the focus on the conclusion predicted from evidence; わけだ focuses more on understanding why the situation makes sense.

Contrast with nearby expressions

Form	Main function	Example idea
〜はずだ	Logical expectation based on information	The train should arrive at ten.
〜と思う	Personal thought or ordinary prediction	I think the train will arrive soon.
〜だろう / 〜でしょう	Prediction or probability	The train will probably be late.
〜そうだ	Appearance based on what is visible	The train looks crowded.
〜べきだ	Duty, ideal action, or strong advice	You should keep your promise.
〜ことになっている	Rule, arrangement, or established procedure	The train is scheduled to leave at ten.

These categories can overlap in real contexts. Choose according to what you want to foreground: evidence-based expectation, probability, visible appearance, duty, or an established rule.

Practice Tips

1. State the evidence first. Make pairs such as 時刻表では九時です。九時に着くはずです。 This trains the reasoning behind はず instead of only memorizing its English translation.
2. Drill the four attachment patterns. Replace one item at a time: 来るはず, 安いはず, 便利なはず, 休みのはず. Pay special attention to な and の.
3. Build negative pairs. Compare 行かないはずです with 行くはずがありません and explain the difference aloud: “expected not to go” versus “cannot possibly go.” Then add past forms such as 行ったはずです.

Related Concepts

• Prerequisite: Plain/Dictionary Form — provides the verb and adjective forms used before はず.