Kitchen stone bench tops - what width 20mm or 40mm?

[Sparrow8]

Hi, we are renovating our kitchen and are having stone bench tops with an undermount sink. The friend of a friend who is supplying the kitchen units needs to know what thickness bench top we are going for so that the cupboards are the correct height.

We didn't realise there were different thicknesses! So what is the norm? Should we go for 20mm or 40mm? Is there a thickness we need in order to have an undermount sink?

Please help!!

Thanks

it doesn't matter what size top you select for the height of the units.
plinth height is a max 150mm
units approx 720mm = 870mm

I have an undermount sink and the worktop is 40mm. Get the thickest ones you can, they look beautiful and substantial. A thin worktop looks mean and skimpy looking. The stone and undermount sink are fantastic, great choice!