Japanese Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Japanese language. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

うちに has two rather confusingly different meanings.

One is in line with its never seen kanji form. Whilst. Do x whilst y.

Another means do x before y's situation changes.

The two are quite different as to when x should be done. Is there a way to spot which is meant?

share|improve this question
Short answer: look at the context. They are not that confusing - do you have a text book and a few model examples? BTW: There is one other use which is a slightly different; to describe a change that happen while something was in progress that was not of the main actor's volition. – Tim Jul 5 '14 at 10:52
I see "while" and "before the situation changes" as basically the same thing. Or at least while it's in present tense. – Kevin Jul 5 '14 at 23:23

For example,

Do x whilst y
[明]{あか}るいうちに(≒明るい[間]{あいだ}に)[帰]{かえ}ってきなさい。(Come back while it's bright)
[温]{あたた}かいうちに(≒温かい間に)食べなさい。(Eat while it's warm)
子どもが[寝]{ね}ているうちに(≒寝ている間に)[洗濯]{せんたく}します。(I do the laundry while the child is sleeping)

can be rephrased:

Do x before ys situation changes
[暗]{くら}くならないうちに(≒暗くなる[前]{まえ}に)帰ってきなさい。(Come back before it gets dark)
[冷]{さ}めないうちに(≒冷める前に)食べなさい。(Eat before it gets cold)
子どもが[起]{お}きないうちに(≒起きる前に)洗濯します。(I do the laundry before the child wakes up)

(Use a negative form for the latter format.)

share|improve this answer
In my opinion, the second case is best thought of as equivalent to the English "while" as well: While it is not (yet) dark, come back. – Muhd Jul 16 '14 at 0:30

I don't think those meanings sound very different, but if you were to give some examples we would be better able to address your question.

~うちに can be used in a number of (grammatical) situations, and in almost all of those it can be understood in English1 as "while".

Kangaete iru uchi ni wakaranaku natta.
(While thinking about it, I got lost.)

However, when ~うちに follows a negative it can be understood in English as "before".

Ame ga furanai uchi ni tenisu o shite kimasu.
(I'll go and play tennis (and come back) before it rains.)

Additionally, when ~うちに is preceded by something for which the beginning and ending is certain, ~間【あいだ】に can be substituted.

Kodomo ga gakkou ni itte iru uchi ni / aida ni hon o yomimasu.
(I read books while my child is away at school.)

I hope this answers your question. If not, I am more than willing to expand it.

1 Though as a matter of personal opinion, I don't believe this is the best way to understand things in a foreign language.

Makino, Seiichi and Tsutsui, Michio. "A Dictionary of Basic Japanese Grammar". Japan Times, 1994.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.