The short answer
English uses “should” for three different jobs, and Japanese splits them. はずだ is a prediction: based on what you know, something is expected to be true. べきだ is a judgment about what is right or proper, often a general principle. ほうがいい is practical advice for a specific situation: doing this will work out better for you.
If you can replace “should” with “is supposed to / I expect”, use はずだ. If you can replace it with “ought to, as a matter of principle”, use べきだ. If you can replace it with “you’d better / it’d be a good idea to”, use ほうがいい.
| はずだ | べきだ | ほうがいい | |
|---|---|---|---|
| Meaning | expected to be, supposed to be | ought to, the right thing is | had better, it’s a good idea to |
| Typical use | predictions, reasoning from facts | morals, duties, opinions | advice to a specific person |
| Example | 電車はもう来るはずだ。 The train should be here soon. | 約束は守るべきだ。 You ought to keep your promises. | 早く寝たほうがいい。 You’d better go to bed early. |
はずだ in a nutshell
はずだ expresses what the speaker believes is true or will happen, because the facts point that way. It says nothing about duty. It attaches to the plain form of verbs and い-adjectives, to な-adjectives with な, and to nouns with の: 行くはずだ, 高いはずだ, 静かなはずだ, 休みのはずだ. In polite speech it becomes はずです.
荷物は明日届くはずです。
The package should arrive tomorrow.
彼は十年東京に住んでいたから、道に詳しいはずだ。
He lived in Tokyo for ten years, so he should know his way around.
鍵はかばんに入れたはずなのに、ない。
I'm sure I put the key in my bag, but it isn't there.
べきだ in a nutshell
べきだ states what is right, proper or morally required, usually as the speaker’s opinion or a general rule of conduct. It attaches to the dictionary form of a verb: 言うべきだ, 守るべきだ. する becomes すべきだ or するべきだ. The negative is べきではない (“ought not to”), and べきだった means “should have”, with a strong note of regret or blame. Said directly to someone, べきだ sounds firm and can come across as lecturing.
間違えたら、すぐに謝るべきだ。
If you make a mistake, you ought to apologize right away.
政府はもっと若者の意見を聞くべきだ。
The government should listen more to young people's opinions.
あの時、本当のことを言うべきだった。
I should have told the truth back then.
ほうがいい in a nutshell
ほうがいい compares options and recommends one: “doing this is the better choice for you right now.” It is the everyday way to give advice. For a positive recommendation, use the past (た) form: 行ったほうがいい. For a negative one, use the plain negative: 行かないほうがいい. The dictionary form (行くほうがいい) also exists, but it sounds more like a general comparison than advice to someone. ほうがいいです is still fairly direct, so soften it with と思います or よ depending on the listener.
熱があるなら、病院に行ったほうがいいよ。
If you have a fever, you'd better go to the doctor.
この道は夜暗いから、一人で歩かないほうがいいです。
This street is dark at night, so it's better not to walk it alone.
もっと早く予約したほうがよかった。
It would have been better to book earlier.
Side-by-side examples
The fastest way to feel the difference is to keep the verb and swap the ending.
Add the third option, 田中さんも来たほうがいい, and you get advice: “it would be good for Tanaka to come too”, for example because the meeting affects his project.
言ったはずだ ／ 言うべきだった ／ 言ったほうがよかった
"I'm sure I told you" / "I should have said it (and I'm at fault)" / "It would have been better to say it"
あの店は高いはずだ ／ 値段はもっと安くするべきだ
"That shop should be expensive (from what I know)" / "They ought to make prices lower (in my view)"
彼は行かないはずだ ／ 行くべきではない ／ 行かないほうがいい
"He's not expected to go" / "He ought not to go" / "He'd better not go"
薬を飲んだほうがいい ／ 薬は医者の指示どおりに飲むべきだ
"You'd better take some medicine" (to a friend who's sick) / "Medicine ought to be taken as the doctor instructs" (a general rule)
Notice the negatives: はずだ has two. 行かないはずだ is a mild expectation (“he’s not supposed to go”), while 行くはずがない is a strong denial (“there’s no way he’d go”). べきではない and ないほうがいい never express likelihood at all.
How to choose
- Are you guessing or reasoning about what is or will be true? Use はずだ. No one is being told to do anything.
- Are you telling a specific person what would be good for them right now? Use ほうがいい (た-form for “do”, ない-form for “don’t”).
- Are you stating a principle, a moral view, or what someone failed to do? Use べきだ (or べきだった for “should have”).
- Is the sentence aimed at a superior or a customer? Avoid べきだ, and even ほうがいい. Use a suggestion like 〜てはいかがですか instead.
- Still unsure between べきだ and ほうがいい? Ask whether the reason is “it’s right” (べきだ) or “it’s smart” (ほうがいい).
Common mistakes
"The train should arrive at 3" is a schedule-based expectation. べきです makes it sound like the train has a moral duty.
はずだ can't give advice. The first sentence means "if he's tired, he's expected to rest."
The た-form rule only applies to positive advice. Negative advice uses the plain ない-form.
Telling your boss what they ought to do with べきです sounds like a reprimand. Offer a suggestion instead.
Practice: choose the right one
Show answer
はずだ. You're predicting the result from a fact (daily practice), not telling him what he ought to do.
Show answer
ほうがいい. Practical advice to one person about their situation, and the た-form 帰った is the giveaway.
Show answer
べき. A general moral principle, not a prediction or situational tip.
Show answer
ほうがいい. Negative advice: plain ない-form + ほうがいい. The casual よ also fits friendly advice, not a moral rule.
Show answer
はず. からの + はず marks what you understood the schedule to be, and なのに shows the expectation was broken.
Related grammar to review next
- はずだ: should be; expected to be — the full lesson on expectation, with more reasoning-from-facts examples
- べきだ: should do; must do — formation details like すべき and when べきだ sounds too strong
- ほうがいい: had better or should — more on the た-form vs dictionary-form choice
- はずがない: there is no way that — the strong negative of はずだ, easily confused with はずではない
- べきではない: should not do — the negative of べきだ, compared with ないほうがいい above
- なければならない: must — for rules and requirements that aren’t a matter of opinion, which is where べきだ stops fitting
FAQ about はずだ vs べきだ vs ほうがいい
What is the difference between はずだ and べきだ and ほうがいい?
English uses "should" for three different jobs, and Japanese splits them. はずだ is a prediction: based on what you know, something is expected to be true. べきだ is a judgment about what is right or proper, often a general principle.
How do I choose between はずだ and べきだ and ほうがいい?
Are you guessing or reasoning about what is or will be true? Use はずだ. No one is being told to do anything. Are you telling a specific person what would be good for them right now? Use ほうがいい (た-form for "do", ない-form for "don't"). Are you stating a principle, a moral view, or what someone failed to do? Use べきだ (or べきだった for "should have").