Learn the differences between はずだ (expectation) and べきだ (obligation) in Japanese. Clear examples for JLPT N3.
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Reviewed by GyanMirai Editorial Team•Last reviewed 2025-02-15
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Grammar Comparison JLPT N3 JLPT N3
はずだvsべきだ
はずだ vs べきだ: Japanese Expectation vs Obligation Guide
Master はずだ (expectation/supposed to) and べきだ (should/ought to) in Japanese. Learn the key differences with clear examples and practice exercises.
Read time: 7 min readSearches: 900+ monthlyUpdated: February 18, 2026
Understanding the difference between はずだ (hazu da) andべきだ (beki da) is one of the most important distinctions in Japanese grammar. This comprehensive guide will help you master when and how to use each one correctly.
Grammar Point A
はずだ (hazu da)
Should be / Supposed to be / Expected to (based on reasoning/evidence)
Expresses the speaker's expectation or logical conclusion based on known facts or evidence. Not about obligation — about what you expect to be true.
Core Meaning: はずだ = expectation based on logic/evidence ('it should be true'). べきだ = obligation/strong advice ('you should do this').
2
Obligation vs Expectation: べきだ tells someone what they OUGHT to do (moral/practical advice). はずだ expresses what you EXPECT to be the case (not advice).
3
Subject: べきだ is often about 'you' or 'one' (giving advice). はずだ can be about anyone/anything (making predictions/conclusions).
4
Emotional Tone: べきだ can sound strong, preachy, or judgmental. はずだ is more neutral — just stating what you logically expect.
5
Negative Forms: べきではない = should NOT do. はずがない = can't possibly be (strong doubt). These negatives have quite different nuances.
When to Use Which?
Follow this decision guide to choose the right grammar point.
Yes
Yes
Use はずだ
No
Use べきだ
No
Yes
Use べきだ
No
Use はずだ
Examples with Explanations
はずだ
彼はもう着いているはずだ。
Kare wa mou tsuiteiru hazu da.
He should have arrived by now.
Tip: Expectation based on logic: he left early, so logically he should be there now.
Context: Wondering about someone's arrival
べきだ
学生は毎日勉強するべきだ。
Gakusei wa mainichi benkyou suru beki da.
Students should study every day.
Tip: Obligation/advice: this is what students ought to do.
Context: Giving advice about study habits
はずだ
この店は安いはずだ。
Kono mise wa yasui hazu da.
This shop should be cheap.
Tip: Expectation: based on reviews or past experience, you expect low prices.
Context: Recommending a shop
べきだ
嘘をつくべきではない。
Uso wo tsuku beki de wa nai.
You should not lie.
Tip: Moral obligation: telling lies is wrong, you ought not to.
Context: Moral advice
はずだ
メールは届いているはずです。
Meeru wa todoiteiru hazu desu.
The email should have arrived.
Tip: Logical expectation: I sent it, so it should be in your inbox.
Context: Business email follow-up
べきだ
もっと早く相談するべきだった。
Motto hayaku soudan suru beki datta.
I should have consulted (you) earlier.
Tip: Past obligation/regret: this was the right thing to do, but I didn't.
Context: Expressing regret
はずだ
この問題は簡単なはずだ。
Kono mondai wa kantan na hazu da.
This problem should be easy.
Tip: Expectation: based on the topic or your skill level.
Context: Encouraging someone
べきだ
自分のことは自分でするべきだ。
Jibun no koto wa jibun de suru beki da.
You should do your own things yourself.
Tip: Life advice/principle: this is how one ought to live.
Context: Teaching self-reliance
Common Mistakes to Avoid
Mistake #1Using べきだ for predictions instead of はずだ
Correction: Use はずだ for expectations, べきだ for obligations
べきだ is about what someone SHOULD DO, not what you expect to BE TRUE.
Wrong: 彼はもう来るべきだ。(He should come = obligation?) -- He ought to come (obligation, different meaning)
Correct: 彼はもう来るはずだ。(He should be coming = expectation) -- He should be coming (expectation)
Mistake #2Using はずだ for giving advice
Correction: Use べきだ for 'you should do X'
はずだ doesn't give advice — it states expectations. For advice, use べきだ.
Wrong: 毎日運動するはずだ。(trying to give advice) -- (doesn't make sense as advice)
Correct: 毎日運動するべきだ。 -- You should exercise every day.
Mistake #3Confusing はずがない with べきではない
Correction: はずがない = can't possibly be. べきではない = should not
These negatives are VERY different. One denies possibility, the other prohibits action.
Wrong: Mixing them up -- Confusion
Correct: そんなはずがない (can't be!) vs そうするべきではない (shouldn't do that) -- Different meanings entirely
Mistake #4Using する べき instead of すべき/するべき
Correction: Both すべき and するべき are correct for する
する is special: it can contract to すべき or stay as するべき. Both are fine.
Wrong: N/A — both forms exist -- N/A
Correct: 相談すべきだ = 相談するべきだ -- Should consult (both forms OK)
Memory Tips
Tip 1
Expectation vs Obligation
はずだ = 'based on what I know, this SHOULD BE TRUE.' べきだ = 'based on what's right, you SHOULD DO THIS.'
Example: 電車は来るはずだ (expect it) vs 時間を守るべきだ (keep time = obligation)
Tip 2
Who Benefits?
べきだ gives advice (helps the listener). はずだ shares your expectation (might not be advice at all).
Example: 野菜を食べるべきだ (advice for you) vs 届いているはずだ (my expectation, not advice)
Example: 彼が嘘をつくはずがない (he CAN'T be lying) vs 嘘をつくべきではない (you SHOULDN'T lie)
Practice Exercises
Test your understanding with these practice questions. Click on your answer to see if you are correct.
0 / 6 answered
Q1
彼女は日本語が上手な___。長く住んでいたから。
Her Japanese should be good. She lived there for a long time.
Q2
約束は守る___。
You should keep your promises.
Q3
そんな___がない。彼は絶対にそんなことをしない。
That can't be. He would never do such a thing.
Q4
もっと野菜を食べる___よ。健康のために。
You should eat more vegetables. For your health.
Q5
荷物はもう届いている___です。
The package should have arrived by now.
Q6
子供の前で悪口を言う___ではない。
You shouldn't speak ill in front of children.
Frequently Asked Questions
Yes! はずだ works for expected future events: 明日は晴れるはずだ (It should be sunny tomorrow). It expresses your logical prediction based on information (weather forecast, etc.).
べきだ can sound preachy or lecturing, especially to equals or superiors. For softer advice, use: 〜たほうがいい (it's better to), 〜といい (hope you do). べきだ is fine for clear moral statements or formal/written contexts.
はずだった means 'was supposed to be' — the expectation didn't come true. 今日届くはずだったのに... (It was supposed to arrive today, but...). It expresses failed expectation.
べきだった expresses regret: 'should have done.' もっと早く言うべきだった (I should have said it earlier). It's about a past obligation you failed to meet — often with regret.
べきかもしれない softens it: 'maybe you should.' Also, 〜たほうがいい is much softer everyday advice. べきだ is for when you're making a clear moral/logical point.
Summary
Use はずだ when...
Expresses the speaker's expectation or logical conclusion based on known facts or evidence. Not about obligation — about what you expect to be true.
Use べきだ when...
Expresses strong advice, moral obligation, or what someone ought to do. Implies there's a right action and you're recommending it.
Pro Tip: The best way to master the difference is through reading and listening practice. Pay attention to how native speakers use these grammar points in context.
