中Throughout, all over, or by the end of
中 attaches to a time, place, or group noun and treats that range as a whole. Depending on the sentence, it can mean “throughout,” “all over,” or “by the end of” the named range.
One range, two common interpretations
The verb and particles show how the whole range is being used. With a continuing action or state, the meaning is usually “throughout the range.” With a time expression followed by に and an action that can be completed, the range becomes a deadline window: the action must be completed before that range ends.
Throughout a time or place
Here the action or state extends across the named range.
Completion before the range ends
今日中に返事を送ります。
I will send a reply by the end of today.
AnalyzeSending the reply does not fill the whole day. It is completed at some point within today.
Whole range versus an activity in progress
中 covers an entire time, place, or group range. The same written suffix read 中 instead presents an activity or process as currently in progress. The spelling and following particle alone are not enough to choose the reading.
会議中は電話に出られません。
I cannot answer the phone during the meeting.
AnalyzeThis is the in-progress reading, not the whole-range reading taught on this page.
More examples
昨夜は一晩中雨が降っていた。
It rained all night last night.
Analyze犬が家中を走り回った。
The dog ran all around the house.
Analyzeその歌は日本中で知られている。
That song is known throughout Japan.
Analyzeこの申込書を今週中に提出してください。
Please submit this application form by the end of this week.
Analyze今年中に引っ越す予定です。
I plan to move by the end of this year.
Analyzeクラス中がその知らせに驚いた。
The whole class was surprised by the news.
Analyze