What is the correct punctuation for the phrase: one size fits all?
I have seen two variants:
- 'one size fits all', and
If the phrase is used as an adjective (which it usually is), then hyphenate it:
It is a one-size-fits-all solution.
This hat is one-size-fits-all.
The phrase could be used as an independent clause, however, with "one size" being the subject:
These hats are great. One size fits all, you know.
So in all but the last case, which I imagine is pretty rare, include the hyphens.