How thick is a quartz countertop? The thickness of a stone slab varies from 2cm (little thinner than 1 inch) to 4cm (little thinner than 2 inches). Usually, a thinner slab is used for the backsplash and a thicker slab for the kitchen countertops, but it doesn’t mean that you can’t use the thinner slab for your countertops. If you are considering the installation of a natural stone kitchen countertop whether it is quartz, granite, marble or any other natural stone type check out our competitive pricing and large selection of natural stones to choose from at our Architecture Stones shop in Rockville MD. We make lots of different products on site starting from a kitchen countertop, a vanity top, a shower bench, a fireplace mantel, a custom-made stone sink, a shower threshold, floor and wall tile, wall slabs and finishing with a table top made of natural stone of your choice.