Grammar · Free lesson
By or until: finish by four, stay until five
You promise a finished poster by four. You can also stay available to help until five. Those times do different jobs in your plan.
Professor Scott MendozaThe short answer
Finish by four means finish no later than four; earlier is fine. Be available until five means your availability continues up to five. Choose according to what the time describes: a deadline or the endpoint of a continuing situation.
A deadline is different from a period of availability.
By four sets the latest time for finishing the poster. It does not require you to spend the whole afternoon finishing it. Until five tells someone how long you will remain available. It does not mean you must become available at five.
Read the two promises
I’ll finish the poster by four.
I’ll be available until five.
I finished it at three thirty, so I met the deadline.
Work on the poster until four describes continuing work. It does not promise the poster will be finished by then.
Decide what the clock time controls
Identify the result
finish the poster
Give its deadline
by four
Describe continuing availability
be available until five
Try it now
Match the time to the promise.
Read all answers and explanations
Four is the latest acceptable finishing time. Which sentence gives that deadline?
I’ll finish the poster by four.By four gives the latest completion time. Until four would fit continuing work, not this positive promise to finish. After four is later than the stated deadline.
You are available now and will remain available up to five. Which sentence clearly expresses that continuation?
I’ll be available until five.Until five expresses continuing availability. By five sets a latest time for being available; after five places availability later. Neither clearly states the continuation requested here.
You promised to finish by four. Which statement correctly describes that deadline?
Finishing at three thirty meets the deadline.By four allows an earlier finish, including three thirty. It does not require exactly four, and four thirty is too late.
Put it into practice
Correct both parts of the plan.
The poster must be finished no later than four. You are available now and remain available up to five. Choose the revision that expresses both promises.
I’ll finish the poster until four. I’ll be available by five.
See a model answer
I’ll finish the poster by four. I’ll be available until five.
Choose each preposition for its own message. The two times do not need the same word just because both appear in one plan.
A little more clarity
Common questions
A few useful details before you move on.
Is by four exactly the same as before four?
No. Before four means earlier than four. By four allows four itself as the latest time, as well as earlier times.
Please finish by four; three thirty is fine.
Can I say I won’t finish until four?
Yes. With the negative, not until means not before that time. This says an earlier finish will not happen; it does not give the same promise as finish by four.
I won’t finish until four.
Take it into your day
Finish by four; remain available until five. The deadline allows an earlier finish.
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