でCompletion time or sufficient quantity
This particle marks the amount of time, money, people, or other quantity needed for an event to reach its endpoint. Depending on the context, it often corresponds to “in,” “with,” or “for” in English.
Think about the endpoint
The important idea is not merely that an action continues for a certain duration. The quantity marked by で takes you up to a result: the application is completed, the fever falls, everything is bought, or a task becomes possible.
Time until completion or change
A duration followed by で tells you how long it takes to reach the stated result.
An amount sufficient for a result
The same pattern works with money, people, materials, and other countable amounts.
千円で必要な文房具が全部買えます。
You can buy all the necessary stationery for one thousand yen.
Analyzeこの荷物を運ぶには、三人で十分です。
Three people are enough to carry this luggage.
AnalyzeThe context explicitly presents three as the sufficient number for the task.
この壁はペンキ二缶で全部塗れます。
Two cans of paint are enough to paint this entire wall.
AnalyzeDo not confuse the role of the quantity
After a people count, で can either identify the group acting together or present that number as sufficient for a task. Look for words meaning “enough,” “possible,” or “complete,” and for context that treats the number as a requirement. Also distinguish duration + で, which measures one event up to its endpoint, from a time unit + に, which calculates a recurring frequency or amount per period.
More examples
急行なら、空港まで四十分で着きます。
If you take the express, you will reach the airport in forty minutes.
Analyzeこの問題は暗算なら十秒で解けます。
If you calculate it mentally, you can solve this problem in ten seconds.
Analyze注文した本は二日で届きました。
The book I ordered arrived in two days.
Analyze五千円で必要な道具が全部そろいました。
I was able to get all the necessary tools for five thousand yen.
Analyze米二合で、おにぎりが八個作れます。
Two cups of rice are enough to make eight rice balls.
Analyzeこの水は三本で全員に行き渡ります。
Three bottles of this water will be enough for everyone.
Analyzeこの資料は一日でまとめられます。
These materials can be compiled in one day.
Analyze