By vs. Until in English

By vs. Until in English

How do we use the prepositions By and Until in English when they refer to time? Take a look at the following examples:

Write the report until 5 pm.
Write the report by 5 pm. 

Write the report until 5 pm means “Start writing the report now, continue writing it until 5 pm, then stop writing it regardless of whether it is finished or not.”

Write the report by 5 pm means “Make sure that at 5 pm the report is written and finished”. This example makes more sense than the first one.

As a preposition of time by means on or before.
E.g. We will send you the documents by tomorrow.

  • Use “by” when you refer to a deadline.

Until means up to a particular time.
E.g. We have until tomorrow to send out the documents.

  • Use “until” when you refer to the period of time before a deadline.

By is used to describe an action or event that happens on or before a particular moment.
E.g. We expect to know the judgment by the end of June.

Until is used to describe a state or situation in the period of time up to a particular moment.
E.g. The court proceedings are expected to last until June.

You may think of until as referring to the moment a state or situation changes.
E.g. Comments on the draft may be submitted until March 2nd.

Here are some more examples:

  1. I can do it by 3 pm.
              Now   → do it and finish it  3 pm (it will be finished)
  2. I can do it until 3 pm.
              Now   →       do it        3 pm (I’ll stop even if I haven’t finished)
  3. I can’t do it by 3 pm.
              Now   → do it / not do it  3 pm (either way it won’t be finished)
  4. I can’t do it until 3 pm.
              Now   →  can’t do it    3 pm (I’ll start)


Fill in the sentences with by or until:

  1. I need to do the laundry ______ 7pm.
  2. They have ______ March 3rd to move out of their apartment.
  3. We can play ________ he comes home.
  4. My friends are supposed to come _______ next week.


  1. by
  2. until
  3. until
  4. by

If you have any questions or comments regarding us or our classes, please fill out our contact request form

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.