If the firework happens every 30 minutes from 7:00 7:30, 8:00, 8:30, ... 19:00 Can I say: There will be a fireworks display every half hour on the sharp.

2 Answers 2


I've never heard on the sharp before. It would be more idiomatic as: on the dot, or 7:30 -- sharp.

For this pattern, you could say: 7:30 to 9:00, on the half-hour.

Some other ideas:

on the dot and the thirty(-minute mark),
every half-hour, punctually or precisely

  • so can i just say: The firework happens on the half-hour. thx Sep 17, 2013 at 2:35
  • 5
    @walterhuang Either "every half hour", or "on the half hour and the hour".
    – dcaswell
    Sep 17, 2013 at 2:43
  • @user814064 thx Sep 18, 2013 at 1:13

The phrase "every half hour, on the half hour" has the exact meaning you are looking for here.

Sharp relates to punctuality, and as such "at 7:30 sharp" would suggest that failing to arrive at 7:30 would result in a sanction (if you were obligated to do something or be somewhere) or that you would not be waited for and so miss whatever the scheduled event was.

On the dot refers to precision, and as such "at 7:30 on the dot" would mean 7:30 precisely, and not 7:29 or 7:31. Just how precise such precision would be in practice is another matter, but the figurative "dot" here is the precise point in the line or field of possibility.

"On the sharp" is not an idiom on would use, the closest I can think of it is "on the sharp end" meaning the area within a field or issue with the most pressing difficulties.

  • thx for the explanation. i will vote you up when i got 15 rep Sep 18, 2013 at 1:04

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