What Is the Difference Between 「はずがない」 and 「わけがない」? How to Use Two Strong Negative Expressions

When you study Japanese at the JLPT N3 or N2 level, you will encounter expressions that look similar but do not feel exactly the same.

Two common examples are:

• 「はずがない」 (hazu ga nai / cannot possibly be)
• 「わけがない」 (wake ga nai / there is no way)

Consider the following sentences.

田中さんは、そんな簡単なミスをするはずがない。
Tanaka cannot possibly make such a simple mistake.

田中さんは、そんな簡単なミスをするわけがない。
There is no way Tanaka would make such a simple mistake.

Both sentences strongly deny the possibility that Tanaka made a simple mistake.

In English, both can often be translated as “There is no way” or “It cannot be true.”

So what is the difference?

For JLPT grammar and reading comprehension questions, it is not enough to memorize both expressions as strong forms of denial.

The key is to understand what kind of reasoning lies behind the speaker’s conclusion.

The Basic Difference

「はずがない」 (hazu ga nai / cannot possibly be) is commonly used when the speaker judges something to be impossible based on facts, known information, or a reasonable expectation.

「わけがない」 (wake ga nai / there is no way) is commonly used when the speaker strongly rejects an idea because it makes no sense in view of the circumstances, common sense, or the speaker’s firm conviction.

A useful first distinction is:

• 「はずがない」: Based on the available information, it cannot logically be true.
• 「わけがない」: Considering the reasons or common sense, there is absolutely no way it could be true.

However, the two expressions often overlap.

Do not assume that only one of them is grammatically possible in every sentence. In many situations, both can be used, but the emphasis changes slightly.

「はずがない」 Denies an Expected Possibility

The noun 「はず」 (hazu) refers to something that is expected to be true based on information, logic, or a reasonable prediction.

For example:

電車は10時に到着するはずです。
The train is expected to arrive at 10:00.

The speaker may be relying on a timetable or an announcement.

When this idea is negated, we get:

電車が9時に到着するはずがない。
The train cannot possibly arrive at 9:00.

If the timetable says that the train arrives at 10:00, an arrival at 9:00 is inconsistent with the available information.

This is why 「はずがない」 is especially natural when the speaker denies a possibility on the basis of facts or conditions.

Example Sentences

山田さんは今、海外にいる。今日の会議に出席できるはずがない。
Yamada is overseas now. There is no way he can attend today’s meeting.

The fact that Yamada is overseas makes attendance practically impossible.

この店は日曜日が定休日だ。今日、開いているはずがない。
This shop is closed on Sundays. It cannot possibly be open today.

The speaker is using the shop’s schedule as evidence.

彼女はまだ出発していない。もう駅に着いているはずがない。
She has not left yet. She cannot possibly have arrived at the station already.

The conclusion is based on the sequence of events.

「わけがない」 Expresses a Strong Rejection

The noun 「わけ」 (wake) refers to a reason, explanation, logic, or circumstance.

Therefore, 「わけがない」 literally suggests that there is no reasonable basis for something to be true.

It is used when the speaker strongly rejects an idea as impossible, unreasonable, or completely inconsistent with what they know.

Example Sentences

毎日一生懸命練習している彼が、簡単にあきらめるわけがない。
There is no way someone who practices hard every day would give up so easily.

The speaker knows the person’s attitude and strongly rejects the idea that he would quit.

そんな高価な車を、学生の私が買えるわけがない。
There is no way a student like me could afford such an expensive car.

The speaker is emphasizing that the idea is unrealistic.

あれほど慎重な人が、何も考えずに決めたわけがない。
There is no way such a cautious person made the decision without thinking.

The speaker’s conclusion is based on the person’s character.

「わけがない」 often carries a stronger sense of personal conviction.

The speaker is not merely saying that something is unlikely. The speaker is saying that it makes no sense to believe it.

Compare Them in Similar Situations

The difference becomes clearer when the expressions are compared in similar contexts.

Example 1: Coming to Work

田中さんは昨日入院した。今日、会社に来るはずがない。
Tanaka was hospitalized yesterday. He cannot possibly come to work today.

The speaker is making a logical judgment based on an objective fact: Tanaka is in the hospital.

あれほど体調が悪かった田中さんが、無理をして会社に来るわけがない。
There is no way Tanaka would force himself to come to work when he was feeling that unwell.

The speaker is strongly rejecting the idea based on Tanaka’s condition and expected behavior.

Example 2: Passing an Exam

彼は試験を受けていない。合格するはずがない。
He did not take the exam. He cannot possibly have passed it.

The result is logically impossible because he did not take the exam.

ほとんど勉強していない私が、満点を取れるわけがない。
There is no way I could get a perfect score when I have barely studied.

The speaker is emphasizing how unrealistic the idea is.

A Practical Tip for JLPT Reading Questions

In JLPT questions, pay close attention to the information immediately before the blank.

「はずがない」 is often a strong choice when the passage includes:

• A schedule or deadline
• A rule or system
• A location or distance
• A confirmed fact
• Previously established information
• A sequence of events

「わけがない」 is often a strong choice when the passage includes:

• A person’s personality or values
• The speaker’s strong conviction
• Common sense
• A rhetorical rejection
• Expressions such as 「そんな」 (sonna / such a thing) or 「いくらなんでも」 (ikura nandemo / no matter how you look at it)

Consider this example.

彼はまだ一度も日本語を勉強したことがない。難しい漢字が読める＿＿＿。
He has never studied Japanese before. He cannot possibly read difficult kanji.

A natural answer is:

読めるはずがない。
He cannot possibly read them.

The conclusion follows from an objective fact: he has never studied Japanese.

Now compare this sentence.

毎日努力している彼が、こんな小さな失敗で夢をあきらめる＿＿＿。
There is no way he would give up his dream because of such a small failure when he works hard every day.

A natural answer is:

あきらめるわけがない。
There is no way he would give up.

The speaker is strongly rejecting the idea based on the person’s character and effort.

Do Not Oversimplify the Difference

It is tempting to memorize the following rule:

• 「はずがない」: logical and objective
• 「わけがない」: emotional and subjective

This shortcut is useful at first, but it is not always accurate.

「わけがない」 can be used in calm, logical statements.

パスワードを知らない人が、本人の許可なくログインできるわけがない。
There is no way someone who does not know the password can log in without the user’s permission.

This is not an emotional statement. The speaker is relying on the logic of the system.

Similarly, 「はずがない」 can express strong personal trust.

私の友人が、そんなひどいことを言うはずがない。
My friend cannot possibly have said something so cruel.

The speaker’s belief is connected to trust in the friend.

The real question is not simply whether the sentence sounds emotional.

Ask yourself:

• Is the speaker denying an expected possibility based on information?
• Is the speaker rejecting the idea as something that makes no sense?

That distinction will help you understand the intended nuance.

How to Form the Expressions

Both 「はずがない」 and 「わけがない」 can follow verbs, adjectives, and nouns.

After a Verb

彼が約束を忘れるはずがない。
He cannot possibly forget his promise.

彼が約束を忘れるわけがない。
There is no way he would forget his promise.

After an い-Adjective

この商品が、こんなに安いはずがない。
This product cannot possibly be this cheap.

この商品が、こんなに安いわけがない。
There is no way this product is this cheap.

After a な-Adjective

試験が簡単なはずがない。
The exam cannot possibly be easy.

試験が簡単なわけがない。
There is no way the exam is easy.

After a Noun

あの人が学生のはずがない。
That person cannot possibly be a student.

あの人が学生なわけがない。
There is no way that person is a student.

Pay particular attention to the form used after nouns.

Do Not Confuse 「わけがない」 with 「わけではない」

「わけがない」 (wake ga nai / there is no way) and 「わけではない」 (wake dewa nai / it does not mean that) look similar, but their meanings are very different.

「わけがない」

This is a strong denial.

彼がそんなことを言うわけがない。
There is no way he would say something like that.

The speaker rejects the possibility.

「わけではない」

This is used to avoid a complete or overly simple conclusion.

甘いものが嫌いなわけではない。
It is not that I dislike sweet foods.

The speaker is saying that the situation is more nuanced.

The difference between 「が」 and 「では」 completely changes the meaning. Always read the particles carefully.

Do Not Confuse 「はずがない」 with 「はずではない」

「はずがない」 (hazu ga nai / cannot possibly be) and 「はずではない」 (hazu dewa nai / is not supposed to be) are also different.

「はずがない」

This strongly denies a possibility.

彼が犯人のはずがない。
He cannot possibly be the culprit.

「はずではない」

This indicates that something is inconsistent with an expected schedule, plan, or situation.

電車は、まだ出発するはずではない。
The train is not supposed to leave yet.

JLPT questions often test whether you notice these small but important differences.

Mini Quiz

Choose the more natural expression: 「はずがない」 or 「わけがない」.

Question 1

この美術館は月曜日が休館日だ。今日、入れる＿＿＿。
This museum is closed on Mondays. There is no way we can enter today.

Answer:

入れるはずがない。
We cannot possibly enter.

The conclusion is based on the museum’s schedule.

Question 2

家族を大切にしている彼が、理由もなく子どもの誕生日を忘れる＿＿＿。
There is no way someone who cares deeply about his family would forget his child’s birthday for no reason.

Answer:

忘れるわけがない。
There is no way he would forget.

The speaker is strongly rejecting the possibility based on the person’s values.

Question 3

彼女はまだ出発していない。もう駅に着いている＿＿＿。
She has not left yet. She cannot possibly have arrived at the station already.

Answer:

着いているはずがない。
She cannot possibly have arrived.

The sequence of events makes the situation impossible.

A Simple Checklist for JLPT Questions

When you are unsure which expression to choose, ask yourself these questions:

1. Is there a concrete fact, rule, schedule, or condition?
2. Is the speaker denying a possibility based on expected logic?
3. Is the speaker strongly rejecting the idea because it makes no sense?
4. Is the sentence based on someone’s personality, values, or common sense?
5. Could the test be asking about 「わけではない」 or 「はずではない」 instead?

As a starting point, remember:

• Use 「はずがない」 when information leads you to conclude that something cannot be true.
• Use 「わけがない」 when the idea itself is strongly rejected as unreasonable or impossible.

Conclusion

Both 「はずがない」 and 「わけがない」 express strong denial.

However, their focus is slightly different.

• 「はずがない」: Based on facts or expectations, the possibility is logically denied.
• 「わけがない」: Based on reasons, common sense, or firm conviction, the idea is strongly rejected.

Understanding this difference will help you not only with grammar questions but also with reading comprehension.

In JLPT reading passages, knowing the dictionary meaning of each word is not enough. You also need to understand why the writer chose one expression instead of another.

RJT (Rapid Japanese Training) helps you build that skill through repeated practice with real questions.

Do not stop after reading the explanation. Choose an answer, notice where you hesitate, and check the reason carefully.

That process will help you make faster and more accurate decisions on test day.

Related grammar guide: JLPT Inference and Judgment Expressions

Practice similar JLPT grammar questions and strengthen your reading skills with RJT

For a broader overview of negative patterns, see the guide to confusing JLPT negative expressions. Confusing JLPT Negative Expressions