Stone Slab Weight Calculator
Estimate what a granite, marble, quartzite, or quartz slab weighs — per slab and in total — from its area, thickness, and stone type.
Estimated slab weight
Weight is area × thickness × stone density, at the heavy end of each stone's range so the figure errs heavy. Slabs are moved and set by trained installers with proper equipment, and cabinets and floors must be checked for the load.
Why weight is a planning number, not an afterthought
Stone is heavy in a way that surprises people the first time they lift a slab. A physics estimate — area times thickness times density — gives you a realistic figure well before delivery, so you can plan the handling: how many people, what lifting gear, and whether the cabinets and subfloor underneath are up to the load.
Density is what separates the stones. Granite, marble and quartzite run from about 2.55 to 2.8 g/cm³, the dark black granites nearer 3.0, and engineered quartz lower at about 2.3 to 2.5; this calculator plans at the heavy end of each range. Multiply by thickness and it's clear why 3 cm stone weighs so much more than 2 cm, and why slabs are moved and set by trained installers with proper equipment, never by brute force.
Frequently Asked Questions
How much does a stone slab weigh?
Weight is volume times density. This tool converts your area to square centimetres, multiplies by thickness to get volume, then by the stone's density. At the densities it uses, a true 3 cm of granite or marble works out to about 17 pounds per square foot (about 18 at a full 1¼ inch), 2 cm to about 11½, and 3 cm engineered quartz to about 15. Dark black granites run heavier, about 18½ at 3 cm.
What densities does this use?
It uses planning densities at the heavy end of each stone's common range, in grams per cubic centimetre: granite 2.80, black granite (gabbro and diabase) 3.00, marble 2.80, quartzite 2.70, and engineered quartz 2.50. Real stone varies between quarries and colours; erring heavy means the estimate should not send too few hands or too little equipment to a lift.
Why does slab weight matter?
It determines whether your cabinets and floor can carry the load, how many people and what equipment are needed to move the stone safely, and whether a vehicle can transport it. A single 3 cm granite countertop can weigh several hundred pounds, so knowing the number before delivery day is a safety issue, not just a curiosity.
Is 2 cm or 3 cm stone better?
3 cm (about 1¼ inch) is the common thickness for countertops in much of North America and can often span cabinets without extra plywood support. 2 cm is lighter and cheaper but usually needs a plywood substrate or a built-up edge to look substantial. The right choice depends on your cabinets, your look, and your fabricator's recommendation.
Does the finished countertop weigh the same as the slab?
Roughly, minus the material cut away for sink and cooktop openings and the offcuts. The per-square-foot figure is the useful one for checking cabinet loading. Add the weight of any built-up (laminated) edge, which effectively doubles the thickness along the front.
Educational estimate — actual density varies by quarry and finish. Verify a slab's true weight and follow safe-handling practice before lifting or loading.