How to tell them apart
までに marks a deadline by which something is completed, focusing on a fixed point in time. うちに highlights an ongoing state or window that will not last, urging action before it changes. For example, 3時までに来てください sets a deadline while 若いうちに勉強する means study while young, and swapping them is unnatural.
- までに Use までに to mark a specific deadline or point by which an action is completed.
- うちに Use うちに to act during a limited window before a situation changes or ends.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| までに madeni | no later than a set time or deadline | N4 |
| うちに uchini | during the time something holds; before the chance is gone | N3 |
までに madeni
no later than a set time or deadline
までに marks a deadline and means no later than that point, used when an action must be completed before a set time. It follows a time noun as in 4時までに or 明日までに, or the dictionary form of a verb as in 着くまでに. Unlike まで, which describes an action continuing up to a time, までに stresses completion before the deadline, so it often appears with verbs of finishing.
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早く始めれば昼飯までに終えられる。
If we begin early, we can finish by lunch.
-
今週までにはそれを終えてしまいたかったのだが。
I hoped to have finished it by this week.
うちに uchini
during the time something holds; before the chance is gone
うちに expresses doing something while a state or opportunity lasts, before it changes and the chance is lost. It follows the non-past form of verbs, including negatives like 帰らないうちに and ongoing actions like 歩いているうちに, i-adjectives like 若いうちに, na-adjectives with な, and nouns with の like 朝のうちに. The main clause often describes an intentional action taken advantage of that limited time.
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チャンスがあるうちに私の警告を聞くべきだったんだよ。
You should have listened to my warning when you had the chance.
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若いうちにたくさんの本を読むべきだ。
While you're young, you should read a lot.
までに and うちに are JLPT N4–N3 grammar points that Japanese learners often mix up. This page compares them side by side on meanings, usage and example sentences, so you can tell them apart.