Tile Calculator

Enter the area, the tile size and the grout joint, choose a waste allowance for the layout you are using, and get the tile count, the number of boxes to buy and an estimate of adhesive and grout.

Works for any tile size, in inches or millimetres, and for straight, diagonal and herringbone layouts.

How to use the tile calculator

Why use the Build Tally tile calculator

Counting tiles instead of dividing areas

Dividing room area by tile area under-counts, because every tile at the edge of the room is cut and its offcut usually cannot be used elsewhere. The tool works from tile size including the grout joint, then applies a waste allowance for the layout — and that allowance is where the layout really matters. A straight stack in a plain rectangular room wastes about 10%; diagonal and herringbone patterns cut every perimeter tile at an angle and need 15% or more.

Layout decisions that change the count

Where you start the first tile determines how wide the cut tiles at the far wall end up. The usual approach is to centre the layout so both edges get an equal, reasonably wide cut rather than starting flush at one wall and finishing with a 15 mm sliver at the other. Dry-lay a row before you spread any adhesive. In a bathroom, set out from the most visible line — often the front of the bath or the shower wall — rather than from a wall that turns out not to be straight.

Adhesive, grout and batch matching

Adhesive coverage depends on trowel notch and tile size: roughly 40–50 sq ft per 50 lb bag with a 1/4 in notch, considerably less with a large-format trowel. Grout depends on joint width and tile thickness, so wide joints on thick porcelain use much more than a thin joint on a small wall tile. Buy all your tile in one order — shade varies between production batches, and a replacement box bought later can be visibly different under the same light.

Read the guide: How to Calculate Square Footage of a Room, a House or a Yard