the difference between words: until and by


There is a common misunderstanding in Japan and Korea (and possibly in other countries as well) about the difference between “until” and “by”, so I’d like to explain the difference today. The word “until” refers to the time when some action stops, but the word “by” refers to a deadline when an action must be stopped. For example:

I worked until 8:00 p.m. last night.

I’m going to keep my part-time job until I graduate from university.

I’ll be in Osaka until Thursday, and then I’ll go back to Tokyo.

You can borrow my CD, but please give it back to me by the end of the month.

This project must be completed by Friday, March 26th.

A: What time do I need to check out of my room by?

B: By 11:00 a.m. please.

We also use “by” in the expression “by the time…” which is similar in meaning to “when”.  For example:

By the time I got to the office, the meeting had already started.

I had already finished my work by the time the boss called me.

Everyone had already started eating by the time I arrived at the restaurant.

By the time you get this message, I will already have left the office.

By the time I’m 50, I will have started my own company.

These last examples are a little bit more difficult because they use more complex tenses (had + pp and will have + pp). If you feel uncomfortable using them, try using the method I explained in my first blog: memorize the examples and then change the small details of the sentences to make new sentences. The important thing is that you don’t think in your native language. If you start thinking in your native language, you’ve changed the sentence too much! Good luck!


  1. U-key Said:

    Can I question?
    “until” and “till” are same mean?

    • Yes, “until” and “till” are the same thing but “until” is the regular word and “till” is the more casual version which is often used in conversational English. In formal written English, we only use “until”.

      • U-key Said:

        It has understood well. Thank you!
        Have a good weekend.

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