[ojm]

You get less inches than cm. Less miles than km.

Not so free after all!

[duncan_bayne]

I was going to reply "fewer inches!" but then I realised that inches are (at least in principle) not discrete; half an inch is a perfectly reasonable measurement.

Anyone here know which of "less inches" or "fewer inches" is grammatically correct?

[skj]

"fewer" is for things you can count.

Less length, but fewer inches.