What it means
はずだ expresses a strong expectation or conclusion based on information, plans, rules, or a reasonable understanding of a situation. It means that something is expected to be true, rather than that someone is required to do it. It can be used with verbs, nouns, na-adjectives, and i-adjectives. The polite counterpart is はずです.
Usage note
はずだ describes what the speaker expects or believes should be true. Do not confuse it with べきだ, which expresses what someone ought to do. With nouns and na-adjectives, use のはずだ and なはずだ, respectively.
How to use it
彼は医者のはずです。
He is expected to be a doctor.
この部屋は静かなはずです。
This room is expected to be quiet.
この問題は難しいはずです。
This problem is expected to be difficult.
電車は八時に着くはずです。
The train is expected to arrive at eight o’clock.
彼は医者のはずだ。
He is expected to be a doctor.
この部屋は静かなはずだ。
This room is expected to be quiet.
この問題は難しいはずだ。
This problem is expected to be difficult.
電車は八時に着くはずだ。
The train is expected to arrive at eight o’clock.
Example sentences
来週の月曜日には、新しい図書館が開館するはずです。
The new library should open next Monday.
天気予報によると、明日は午後から雨が降るはずです。
According to the weather forecast, it should rain from the afternoon tomorrow.
予約した電車は、もう駅に着いているはずです。
The train I reserved should have already arrived at the station.