not longer vs no longer

Is it correct to say 'not longer than' as well as 'no longer than'? I think I read somewhere that it's 'no more than' and not 'not more than'.

Both 'not longer than' and 'not shorter than' are acceptable in some contexts.

Here's the context. The sentence I am trying to correct is:
'Your contents are insured when they are outside your flat not longer than three months.'

Julie17 said:

Here's the context. The sentence I am trying to correct is:
'Your contents are insured when they are outside your flat not longer than three months.'

Click to expand...

'Not longer than' is acceptable here, as is 'no longer than'. Actually, if this is part of a contract, it's more likely to be something along the lines of '... when they are outside your flat for a perid not exceeding three (calendar) months' (or, 'ninety days'.)

Thanks. I know the original sentence is not good, but as long as there are no grammar etc mistakes I'm quite happy. ;-)

By the way, would the phrase 'not more than' be correct in this context, too?
'.... if you are away for not more than three months.'

Yes