JapaneseJLPT
JLPT N3 grammar · Chapter 16

～のだから

Emphasize a known reason before drawing a conclusion

You’ll be able to treat a fact as shared or established and use it to support advice, expectation, or judgment.

Illustration of the scene described by Since we came all this way, let's take a photo.
Read it first

ここまで来きたのだから、写真しゃしんを撮とりましょう。

koko made kita no da kara, shashin o torimashou.

What do you think this sentence means?

Since we came all this way, let's take a photo.

Why it means that

Base a conclusion on an established fact

～のだから (or ～んだから) emphasizes a known, evident fact or shared reality as the premise for a natural conclusion, request, advice, or judgment ("since... is clearly the case, obviously...").

Examples

約束やくそくしたんだから、守まもらなければいけないよ。

yakusoku shita n da kara, mamoranakereba ikenai yo.

You promised, so you have to keep it.

せっかく作つくったんだから、たくさん食たべてね。

sekkaku tsukutta n da kara, takusan tabete ne.

I went to the trouble of making it, so eat lots.

How it is built

Attach のだから to plain form

Attach のだから (or conversational んだから) to plain forms of verbs, adjectives, or nouns (noun/な-adjective uses なのだから). The second clause often expresses advice, a command, or a natural expectation.

plain form+のだから／んだから
Example

熱ねつがあるのだから、今日きょうは無理むりをしないで休やすんでください。

netsu ga aru no da kara, kyou wa muri o shinaide yasunde kudasai.

Since you have a fever, please don't overdo it today and get some rest.

Compare

～から vs ～んだから

～から just gives a reason. ～んだから points to a fact both people already know and uses it to push a conclusion, often advice or a mild scolding.

  • ～から, because

    雨あめだから、傘かさを持もっていきなさい。

    ame da kara, kasa o motte ikinasai.

    It’s raining, so take an umbrella.

    A plain reason.

  • ～んだから, since (obviously)

    雨あめなんだから、傘かさを持もっていきなさい。

    ame na n da kara, kasa o motte ikinasai.

    It’s raining, you know — so take an umbrella.

    The rain is plain to see, so the advice sounds firmer.

Examples

「自分じぶんで選えらんだ仕事しごとなんだから、もう少すこし頑張がんばってみたら？」

“jibun de eranda shigoto na n dakara, mou sukoshi ganbatte mitara?”

“It’s a job you chose yourself, so why not try a little harder?”

道みちが分わからないんだから、誰だれかに聞きいたほうが早はやいよ。

michi ga wakaranai n dakara, dareka ni kiita hou ga hayai yo.

You don’t know the way, so it’s quicker to ask someone.

「お兄にいちゃんなんだから、弟おとうとにも少すこし分わけてあげなさい。」

“oniichan na n dakara, otouto ni mo sukoshi wakete agenasai.”

“You’re the big brother, so share some with your little brother.”

7 more examples in the grammar path — free for a limited time.