Countertop Calculator

How countertop is measured

Length times depth, per run, in inches, divided by 144 to get square feet. Depth is measured to the front edge including the overhang, which on a standard 24 inch base cabinet comes to about 25 inches with a 1 inch nose. Add the backsplash as its own rectangle if you are having one in the same material.

A typical L-shaped kitchen with a 96 inch run and a 60 inch run at 25 inches deep is 27.08 square feet of counter. Add a 4 inch backsplash along all 156 inches and that is another 4.33, so 31.42 square feet in total. At a 10 percent fabrication allowance the fabricator works from 34.56.

Why the number you measure is not the number you pay for

Stone comes in slabs, and slabs come in fixed sizes, commonly around 55 by 120 inches. A fabricator does not sell you 31.42 square feet of granite; they sell you the slabs your layout consumes, and what is left over after the cuts is theirs to absorb or yours to pay for depending on the shop.

The practical consequence is that square footage is a poor way to compare quotes. Two kitchens a few square feet apart can need the same number of slabs and cost the same, or fall either side of a slab boundary and differ by a thousand dollars. Ask each fabricator how many slabs your layout takes, and whether the remnant is credited.

What the allowance covers

Ten percent is a reasonable default and it is not waste in the usual sense. It covers cutting the sink and cooktop openings out of otherwise usable material, the trim on each piece, and matching veining across a seam, which on a heavily figured stone can consume a great deal more than 10 percent. Quartz is more forgiving than natural stone because the pattern is consistent, so a plain quartz can run closer to 5 percent while a dramatic marble can want 20 or more.

What is not in this number

Edge profile, sink cutouts, cooktop cutouts, and the tear-out of whatever is there now are all usually priced separately, per linear foot or per opening rather than per square foot. So are seams. A quote that looks low per square foot and adds those back is not cheaper, it is itemised differently, and the only way to compare two is to get both to the same scope. Our countertop cost guide prices each material per square foot installed, along with the cutouts, edges and removal a quote adds.

Tiling the backsplash instead of running the counter material up the wall? Our tile calculator gives the tile and grout, and the thinset calculator sizes the mortar from the trowel notch.