～わけだ

How to form it

• Verb / い-adjective (plain form) + わけだ
• な-adjective + な + わけだ
• Noun + な / である + わけだ

Register: Neutral

Explanation

Shows that something is a natural conclusion or that the speaker understands the reason after hearing a fact.

It is used for the moment of understanding, 'so that is why', or for restating something in other words. It often follows a fact and a conclusion.

Examples

1. 十年日本に住んでいたのか。日本語が上手なわけだ。

   じゅうねんにほんにすんでいたのか。にほんごがじょうずなわけだ。

   You lived in Japan for ten years. No wonder you are good at Japanese.

2. 夜遅くまで働いていたなら、眠いわけだ。

   よるおそくまではたらいていたなら、ねむいわけだ。

   If you were working until late, no wonder you are sleepy.

3. 彼は私の兄の友達だから、私とも知り合いというわけだ。

   かれはわたしのあにのともだちだから、わたしともしりあいというわけだ。

   He is my brother's friend, so he is also an acquaintance of mine.

4. 一年は十二か月だから、二年は二十四か月なわけだ。

   いちねんはじゅうにかげつだから、にねんはにじゅうよんかげつなわけだ。

   A year is twelve months, so two years comes to twenty-four months.

Compare with

• ～はずだ: はずだ is an expectation; わけだ is a conclusion reached from a fact.

Common mistakes

• Using it for a new, unrelated fact. わけだ follows from the preceding information.