This is a sentence ending. You use it to explain something. You also use it to give a reason. It sounds casual.
Verb [dictionary form] + んだよPrimary
い-Adjective + んだよ
な-Adjective + なんだよ
Noun + なんだよ
This is a sentence ending. You use it to explain something. You also use it to give a reason. It sounds casual.
どうして電話に出なかったの？仕事がすごく忙しかったんだよ。
Why didn't you answer the phone? I was incredibly busy with work.
もう帰るの？うん、明日も朝早いんだよ。
Are you going home already? Yeah, I have to get up early tomorrow too.
そんなにたくさん食べられないんだよ。もうお腹いっぱいだから。
I can't eat that much, you know. I'm already full.
これはただの石じゃない。僕の宝物なんだよ！
This isn't just a rock. It's my treasure!
A: なんで勉強しなきゃいけないの？ B: いい大学に入って、いい仕事に就くためなんだよ。
A: Why do I have to study? B: It's so you can get into a good university and get a good job.
This phrase is like a strong statement. Men and boys often use it. If you want to sound softer, you might choose a different phrase.
This is different from "~nda." The "yo" makes you explain to the listener directly. It is stronger than just "~nda." It is not as strong as "~ndazo." That is a very strong warning. It is like "~ndesuyo" but for casual talk.
Watch out: Do not use 「〜んだよ」 with people you should be polite to. This includes teachers or your boss. It sounds too casual. Use 「〜んですよ」 instead when you need to be polite.
Use this when you want to explain something. You think the other person does not know this information. It helps them understand your situation or idea.
Track your mastery
Kumi's KMT system tracks your mastery across kanji, vocabulary, grammar, and reading. Create a free account to use it on 220,000+ concepts.