はずがない

The structure はずがない expresses the speaker's strong conviction that something cannot be true or is highly unlikely. It conveys a sense of disbelief or firm denial based on the speaker's reasoning, knowledge, or evidence. It translates to "there's no way that…", "it can't be that…", or "it is impossible that…".

This is the negative counterpart of はずだ, which expresses an expectation that something should be true. While はずだ means "it should be / it is expected that…", はずがない means "there is no way that… / it can't possibly be…".

Formation

The plain form of verbs, adjectives, and nouns connects to はずがない:

• Verb (plain):いく行く

  • はずがない → 行くはずがない
    かれ彼がそんなことをいう言うはずがない。

    There's no way he would say such a thing.

• い-adjective:やすい安い

  • はずがない → 安いはずがない
    あのみせ店がやすい安いはずがない。

    There's no way that store is cheap.

• な-adjective + な:かんたん簡単

  • な + はずがない → 簡単なはずがない
    このしけん試験がかんたん簡単なはずがない。

    There's no way this exam is easy.

• Noun + の:うそ嘘

  • の + はずがない → 嘘のはずがない
    これがうそ嘘のはずがない。

    There's no way this is a lie.

The past tense of the verb/adjective goes before はず:

Polite form

In polite speech, はずがない becomes はずがありません.

はずがない vs. はずはない

The particle が can be replaced with は for additional emphasis or contrast. はずはない sounds slightly stronger and more emphatic.

Nuance

はずがない is based on the speaker's logical reasoning or strong belief. It is not simply stating a fact but expressing a judgment: "Given what I know, this cannot be true." It is stronger than 〜～ないだろう (probably not) and carries a tone of conviction or disbelief.