By and until are not inertchangeable in English. Although their meaning is almost the same, we use them differently. Take a look at the examples below to find out more.

Tomorrow is the end of year exam.

You have until the end of class today to revise grammar and vocabulary.

You must be here by 8:15 tomorrow morning.

The exam starts at 8:30 and you have until 11 to answer all of the questions.



By is a proposition of time. We use it with specific times or dates to indicate a deadline and in the expression by the time.

  • by + time/date/day = no later than
You must be here by 8:15 tomorrow.


Until and till have the same meaning. Until is more formal than till (’til is the American spelling).

  • until indicates the end of a block of time
You have until the end of class to revise for the exam.
  • use until, till and to as a preposition of time in the expression from … to/till/until
The exam goes from 8:30 to/until/till 11 tomorrow.


By or until can greatly affect the meaning of a sentence.

I’ll be home until 7pm.

I am at home now, but I won’t be here after 7pm.

I’ll be home by 7pm.

I am not at home now, but I will be home any time before or at 7pm.