JLPT N3・N4 Grammar – The difference between “〜あいだに”and “〜うちに”

Table of Contents

1. The difference between “〜あいだに”and “〜うちに”
2. AあいだにB
3. AうちにB
4. Let’s Compare
5. Summary
6. Quiz
7. Similar Articles
8. Comments

Q: Are there any differences between “〜あいだに” and “〜うちに”?

A: Both express that something happens within a certain time or period, but they do not mean exactly the same thing.
“〜あいだに” indicates that B happens at some point during A, while “〜うちに” indicates doing B while A is still continuing, or that an unnoticed change happens while A is going on.
Let’s look at each of them.

AあいだにB (JLPT N4)

[Meaning]
Something is done, or something happens, at some point during the time period A

[Rules]
[V] Verb Dictionary form + あいだに
[V] Verb ている form + あいだに
[A] い adjective + あいだに
[Na] な adjective + な + あいだに
[N] Noun + の + あいだに

[Points]
It is often used for something that happens at one point within a certain period of time.
It is especially common when the time period is relatively clear.

[Examples]　
日本にほんにいるあいだに富士ふじ山さんに登のぼりたいです。
While I’m in Japan, I want to climb Mt. Fuji.

寝ねているあいだに蚊かにさされました。
I got bitten by a mosquito while I was sleeping.

昼休ひるやすみ前まえの人ひとが少すくないあいだに食事しょくじをしてきました。
I had a meal while there were few people before lunchtime.

静しずかなあいだにこの仕事しごとを終おわらせよう。
Let’s finish this work while it is quiet.

夏なつのあいだにダイエットをしよう。
Let’s go on a diet over the summer.

AうちにB (JLPT N3)

[Meaning]
Do B before A changes, or another change happens while A is continuing

[Rules]
[V] Verb Dictionary form・ない form + うちに
[A] い adjective + うちに
[Na] な adjective + な + うちに
[N] Noun + の + うちに

[Examples]　
暗くらくならないうちに帰かえったほうがいいですよ。
You should go home before it gets dark.

若わかいうちに勉強べんきょうしておいたほうがいいですよ。
It’s better to study while you are young.

学生がくせいのうちに色々いろいろなところへ行いきたいなあ。
While I’m still a student, I want to visit many places.

晴はれのうちに洗濯せんたく物ものを干ほそう。
Let’s hang out the laundry while it’s sunny.

“〜うちに” is easier to understand if you think of it in two main ways.

① Do something before the chance is gone

The first is doing something before you lose the chance. It is used when the speaker feels that if they do not do something before the current state ends, the opportunity will be lost. In this meaning, it is also often used together with the ない form of verbs that express change.

[Examples]
桜さくらがきれいなうちに花見はなみに行いこう。

While the cherry blossoms are still beautiful, let’s go see them.
⇒ This shows that once the cherry blossoms fall, it will no longer be possible to enjoy flower viewing in the same way.

アイスが溶とけないうちに食たべたほうがいいよ。

You should eat the ice cream before it melts.

② Another change happens before you realise it

The second is when an unnoticed change or an unexpected result happens while A is continuing.

[Examples]
友達ともだちとゲームをしているうちに夜よるになっていました。

While I was playing games with my friends, it became night.
⇒ This means that I was so focused on the game that I did not notice right away that it had become night.

映画えいがを見みているうちに寝ねてしまいました。

I fell asleep while watching a movie.

しばらく見みないうちに、いとこの背せはわたしより高たかくなっていました。

Before I knew it, my cousin had grown taller than me.

Let’s Compare

Both express something happening within a certain period of time, but they do not mean the same thing.

“AあいだにB” indicates that B happens at some point during the period A.
“AうちにB” indicates that while the state A is continuing, either B is done before that state changes, or an unnoticed change happens while A is going on.

[Example]
◯ 日本にほんにいるあいだに富士ふじ山さんに登さんりたいです。
◯ 日本にほんにいるうちに富士ふじ山さんに登のぼりたいです。
While I’m in Japan, I want to climb Mt. Fuji.

Both sentences are natural, but their nuances are slightly different. “〜あいだに” means that I want to climb Mt. Fuji at some point during my stay in Japan. In contrast, “〜うちに” includes the feeling that I want to climb it before I leave Japan and that I do not want to miss this chance.

Examples where “〜あいだに” sounds natural

[Example]　
◯ 電車でんしゃを待まっているあいだにジュースを飲のみました。
× 電車でんしゃを待まっているうちにジュースを飲のみました。
While waiting for the train, I drank some juice.

Here, “〜あいだに” sounds natural. “Waiting for the train” is a relatively clear and short period of time, and the action “drinking some juice” happens at one point during that time.

Let’s look at some more examples.

[Example]
◯ 昼ひる休憩きゅうけいのあいだに銀行ぎんこうへ行いきました。
× 昼ひる休憩きゅうけいのうちに銀行ぎんこうへ行いきました。
During the lunch break, I went to the bank.
⇒ This is natural with “〜あいだに” because the action takes place within the clearly defined time frame of a lunch break.

わたしが留守るすのあいだに宅配たくはいが来きたようです。
It seems that a delivery arrived while I was out.
⇒ This shows that the delivery came at some point during the time I was away.

Summary

[AあいだにB]

• B happens at some point during the time period A.
• It is easy to use with relatively clear times or periods.
• It expresses an action done or an event that happened within that time.

[AうちにB]

• B is done while the state A is continuing.
• It often includes the feeling of doing something before that state changes.
• It can also express an unnoticed change or an unexpected result that happens while A is going on.

Quiz

Read the following sentence and choose the expression that fits the context from the options provided in the parentheses.

Click on the question to check the answer.

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