Practice JLPTHow to tell them apart
までに marks a deadline by which something must be completed or happens, focusing on a fixed point in time. うちに highlights an ongoing window or state that will not last, urging action before it changes. Swapping them is unnatural: you say 3時までに来てください for a deadline, not 3時のうちに来てください, and 若いうちに勉強する for趁着年轻, not 若いまでに勉強する.
- までに Use までに when you mean a specific deadline or point by which an action is completed.
- うちに Use うちに when you want to act during a limited window before a situation changes or ends.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| までに madeni | By (deadline) | N4 |
| うちに uchini | While; before (an opportunity passes) | N3 |
までに madeni
By (deadline)
By; by the time (when) | A particle that indicates a time limit on/for an action.
-
A:何時までに空港に行けばいいでしょうか。 B:出発の一時間前までに来て下さい。
A: By what time should I go to the airport? B: Please come one hour before departure.
-
ジェット機がパリに着くまでに本を三冊読んでしまいました。
By the time the jet got to Paris, I had finished reading three books.
うちに uchini
While; before (an opportunity passes)
While; before; during | During a period when a certain situation remains in effect.
-
休みのうちによく寝ておきます。
I’ll sleep a lot during the vacation.
-
何もしないうちに今年も終わった・終わりました。
Before I achieved anything, the year has ended.
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 — meanings, usage and example sentences — so you can tell them apart.