Stone Weight Calculator

Weight is volume times stone density. Work out the volume of the piece — length times width times thickness for a slab, or the right formula for a cylinder or boulder — then multiply by the density of the stone, around 160 to 185 lb per cubic foot for most solid stone.

For example, a granite slab 4 by 3 feet by 6 inches thick is 6 cubic feet, and at 168 lb per cubic foot weighs about 1,008 lb. The calculator handles slabs, cylinders and boulders for every common stone type, and gives weight in pounds, tons and kilograms.

Most solid building stone runs about 145 to 185 lb per cubic foot. Sandstone is on the light side at around 145, travertine about 150, limestone about 160, granite, quartzite and marble cluster at 165 to 170, slate about 174, and basalt is heaviest at about 185.

These are for solid stone, not crushed or loose stone, which weighs less per cubic foot because of the air gaps. The by-stone table shows the weight for your exact size across every type at once.

A boulder is roughly a sphere, so its volume is about π ÷ 6 × diameter³ — then multiplied by the stone density. A 2-foot granite boulder is about 4.2 cubic feet and weighs roughly 700 lb; a 3-foot one jumps to about 14 cubic feet and 2,375 lb.

Because volume rises with the cube of the diameter, boulder weight climbs very fast with size — doubling the diameter multiplies the weight by eight. Real boulders are irregular, so treat the sphere as an approximation and lean to the heavy side for rigging.

Among common stones, basalt (bluestone) is the heaviest at about 185 lb per cubic foot, followed by slate at about 174. Sandstone is the lightest at around 145, with travertine near 150.

The popular countertop stones — granite, marble and quartzite — sit close together in the middle at 165 to 170. The spread is only about 28 percent from lightest to heaviest, so size and thickness usually matter more than the stone type for the final weight.

Granite weighs about 168 lb per cubic foot, which works out to roughly 18 lb per square foot for a 1.25-inch (3 cm) slab and about 12 lb per square foot for a 0.75-inch (2 cm) slab.

So a typical 10-square-foot section of 3 cm granite weighs around 180 lb — a real two-person lift. Enter the slab length, width and thickness in the calculator for the exact weight, and switch stones to compare granite against quartzite or marble.

Weight decides whether a piece is a hand carry, a two-person lift or a machine job, and it sets the straps, the dolly and the vehicle. Stone is dense, so even a modest-looking slab or boulder can weigh hundreds of pounds and is easy to underestimate by eye.

For shipping it also drives the freight cost and the pallet limits, since stone is priced and hauled by weight. Knowing the figure up front keeps a lift safe and a load legal.

A short ton is 2,000 pounds, the standard US ton used for stone and aggregate. A metric tonne is 1,000 kilograms, which is about 2,205 pounds — roughly 10 percent heavier than a short ton.

The calculator shows both so you can match whichever your supplier or shipper uses. Confusing the two on a big order can throw your freight and cost estimate off by about 10 percent, so check which ton a quote is in.

Natural stone varies. Density shifts with the grade, the quarry and the porosity — a dense, tight granite weighs more than a porous sandstone of the same size, and two slabs of the same stone can differ slightly.

Shape is the other variable: a boulder is never a perfect sphere, and rough or irregular pieces differ from the clean geometry the calculator assumes. Use the result to plan lifting, rigging and freight, and treat it as a solid estimate rather than a scale reading.