Marble Calculator Guide: Square Footage, Weight & Cost
How to work out how much marble to order for a countertop or tile project, why it weighs what it does, and where the standard 15% waste factor comes from.
Marble is priced and ordered by the square foot, but two projects with the same square footage can need very different amounts of material once thickness and waste enter the picture.
The three numbers that actually matter
- Square footage to order — your bare coverage area plus a waste allowance for seams, edge cuts, and cutouts.
- Weight — area times thickness times marble's density (about 170 lb per cubic foot), which determines whether your cabinets or subfloor need reinforcement.
- Cost — square footage to order times your price per square foot, material only.
Why 15% waste and not 10%
Tile and laminate come in uniform pieces, so a 10% waste allowance usually covers odd cuts at the edges. Marble slabs have natural veining, and matching that veining across a seam often means sacrificing more of the slab than the cut itself would require — 15% is a reasonable planning default for a seamed countertop, though a fabricator working from your actual slab can tell you exactly how much your specific layout will waste.
The Marble Calculator runs all three numbers at once from your length, width, and thickness.