までにBy; no later than
までに marks a deadline: an event must happen at or before the stated time. It does not mean that the event happens at that exact time.
How the deadline works
The time before までに is the latest acceptable point. The main clause therefore usually describes something with a clear completion point, such as submitting a form, finishing work, returning, or making a decision.
Clock, calendar, and event deadlines
会議は午後三時までに終わります。
The meeting will end by 3 p.m.
AnalyzeThe meeting may end earlier; 3 p.m. is the latest point stated.
申込書を金曜日までに提出してください。
Please submit the application form by Friday.
Analyze出かけるまでに、洗濯を終えました。
I finished the laundry before leaving.
AnalyzeLiterally: I finished the laundry by the time I left.
Here, leaving is the event that sets the deadline.
Deadline versus continued duration
With に, the endpoint is a deadline for completing an event. Without に, the activity or state normally continues through the endpoint.
More examples
明日の朝までに返事をします。
I will reply by tomorrow morning.
Analyze試験が始まるまでに席に着いてください。
Please be in your seat by the time the exam begins.
Analyze彼は締め切りまでに原稿を送りました。
He sent the manuscript by the deadline.
Analyze何時までに戻ればいいですか。
By what time should I be back?
Analyze来月末までに新しい住所を知らせます。
I will provide my new address by the end of next month.
Analyze卒業するまでに一度北海道へ行きたいです。
I want to visit Hokkaido once before I graduate.
Analyze