Is 足りるだけ with a negative verb idiomatic?


I've encountered sentences like:

> 「皆【みんな】に足【た】りるだけの椅子【いす】がありません」and
>
> 「皆に足りるだけのコーヒーがありません」.

In English, we wouldn't say, "There aren't just enough chairs," except perhaps
as, "There barely aren't enough chairs," in which case we are emphasizing that
we are just short of the necessary amount. In the context I encountered the
foregoing uses of 「足りるだけ」, this did not seem to be the case, which made me
wonder if this is just idiomatic language.

I guess my question is why is「だけ」is being used here.




「足{た}りるだけ」 is hardly an idiomatic expression.

「だけ」, in this context, means " ** _as many/much_** (to be sufficient for a
given purpose)". It seems you are thinking of its other meaning of " **
_just/only_** ".

> "There are not enough chairs for everyone (to sit on)."

This usage of 「だけ」 is very useful as it enables one to express ideas such as:

「好{す}きな **だけ** 食{た}べなさい。」 = "Please eat as much as you like."

「SEでは、質問{しつもん}したい **だけ** 質問できます。」 = "On SE, you can ask as many questions as
you want."

