Particles · N4
まで vs までに: endpoint or deadline
A small particle difference that changes the time relationship.
In short
まで means an action or state continues up to a boundary. までに means an action should be completed no later than that boundary.
How it works
五時まで働きます means the work continues until five. 五時までに終わります means it will finish by five.
Useful contrast
Think duration/continuation for まで and completion deadline for までに.
Examples
金曜日まで休みです。
I am off through Friday.
金曜日までに出してください。
Please submit it by Friday.
Common pitfall
Using まで when you mean a deadline can imply that the activity continues all the way to that time.