This sentence is from a web site about laser treatments.

"How long a gap do I need between laser hair removal treatments?"

"How long" refers to time anyway.

So, why do we need to say "how long a gap....". I mean would it be also correct if we said "How long do I need between ....."?

  • 2
    Yes, it would be fine. Mar 28, 2023 at 9:35
  • 1
    "an interval" would be an alternative to gap. "What interval should I leave....?" Mar 28, 2023 at 13:48

1 Answer 1


The inference of your statement is that a gap should be left between treatments, presumably for a good reason, ie if you have the treatments too close together it can cause a problem. The focus of the question is on that gap being of adequate length, and if you don't mention the gap it may not make sense. If you just say "how long do I need between treatments?" it raises the question "need for what?" Does something specific have to be done between treatments? If it is just a waiting period, then that needs to be referenced.

If your reason for wanting to omit these words is to shorten the sentence, one alternative would be:

How long should I wait between laser hair removal treatments?

  • you are right this is opinion based, I think "how long do i need between" is perfectly fine, what else could they be talking about except time?
    – WendyG
    Mar 28, 2023 at 10:18
  • Isn't 'begs the question' only an acceptable substitute for 'raises the question in vernacular English, because of the former's formal meaning 'to attempts to support a claim with a premise that itself restates or presupposes the claim'? Mar 28, 2023 at 10:24
  • @WendyG Of course they are talking about time, but time for what? If there needs to be a gap between treatment then that needs to be stated.
    – Astralbee
    Mar 28, 2023 at 11:08
  • The meaning seems clear (at least to me) whether or not you include "a gap", but if you particularly want to emphasise that a gap is required, then explicitly mentioning a gap does that. That said, this is a very trivial question and it doesn't matter much. (In other cases obsessing over the fewest possible words is undesirable and redundancy is useful; in this case there is less value. But this isn't really about English language.)
    – Stuart F
    Mar 28, 2023 at 11:54

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