Tile Calculator

Calculating tile quantities correctly prevents two equally frustrating outcomes: running short mid-project with no matching tiles left at the store, or over-ordering and wasting money. The calculator multiplies your room's square footage by a waste factor that accounts for cuts along edges, diagonal layouts, and breakage during installation. Standard 10% waste applies to simple rectangular rooms with straight-lay tile. Diagonal or herringbone patterns need 15–20% extra because every edge piece requires a 45-degree cut with a large triangular offcut.

Tile size matters more than most people realize when ordering. The actual tile dimensions are slightly smaller than the nominal size printed on the box — a '12×12 inch' tile is typically 11¾ × 11¾ inches. Always enter actual dimensions, not nominal size. Larger format tiles (18×18 inches or bigger) produce fewer grout joints per square foot but require a flatter substrate and are harder to cut around obstacles like toilets and vanities. For bathrooms, 12×24 or 24×48 formats are popular because one row covers a standard tub surround height with a single cut.

One critical rule: buy all your tile from the same manufacturing lot. Color varies subtly between production runs, and mixing lots creates visible lines across your floor or wall. When the calculator shows a quantity, always round up to the next full box — never split boxes. Most retailers accept returns on unopened boxes, so erring slightly high costs nothing if you keep the extra box sealed. For bathroom floors and showers, keep one spare box after installation for future repairs — tile designs get discontinued quickly and finding a match years later is often impossible.

For shower floors and mud-set tile installations, the tile count is only part of the material list — you also need to calculate the mortar bed underneath. Deck mud (also called floor mud) is a dry-pack mixture of coarse sand and Portland cement packed firmly under the tile to create a sloped, rigid base that drains toward the drain. A standard shower floor uses 1–1½ inches of deck mud; at that depth, count on roughly 15–18 lbs of dry mix per square foot — about one 50-lb bag for every 3–4 sq ft. Pre-mixed floor mud bags are available at most home centers and simplify the ratio. Always install a waterproof PVC or CPE liner between the subfloor and the mortar bed before packing mud — skipping this step causes leaks that destroy the subfloor structure within a few years.