Is it impossible to say "I am busy on every Monday" ?

I was told that it's not a grammatically correct sentence.

Someone said "I am busy every Monday" is correct.

Is it true?

Why can't I use "On" in front of "Every Monday" ?

  • 2
    You have to use one or the other. Either "on Mondays" or "every Monday" but not both.
    – Andrew
    Commented Mar 13, 2017 at 4:40
  • You cannot say: on every Monday... If you want to say that you go somewhere on every Monday use on Mondays or every Monday, which are equal expressions. Basically every Monday*=*on Mondays Commented Mar 13, 2017 at 11:47
  • @Andrew I very much disagree. "I am busy on every Monday" is grammatically correct. It's just not colloquial.
    – user91988
    Commented Apr 6, 2020 at 15:48

2 Answers 2


"On every" is not a normal idiomatic phrase in English. As with most idioms, there's no "why" other than "that's how people talk".

Basically you have to use one or the other, either "on Mondays" or "every Monday". These have almost the same meaning:

I play tennis on Mondays (When I play tennis, it's on a Monday, and not usually any other day)

I play tennis every Monday (I always play tennis on Monday, and possibly other days as well)


You could say "I am busy Mondays" meaning EVERY Monday, or you could say "I am busy Monday" meaning just THIS Monday, not every one. But you would not say "I am busy on every Monday" because when you say "I am busy Mondays," it already means EVERY Monday. Just one of those unfortunate things in English where the only explanation is "that's just the way it is..." Obviously "Mondays" is plural so it means ALL the Mondays.

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