Tile Calculator

Tile is sold by the square foot or by the box (with a fixed coverage per box). Calculate the area to cover, divide by tile size, then add a waste factor and round up to whole boxes. A 100 sq ft room with 12-inch × 12-inch tiles needs 100 tiles plus waste — typically 110 tiles ordered, in whatever boxes-of-x the manufacturer ships.

Waste factor recommendations: 10% for simple rectangular rooms with straight edges, 15% for rooms with cuts at edges or fixtures (toilets, vanities), 20% for diagonal layouts, 25% for complex patterns or rooms with many obstacles. Set aside the actual leftovers as dye-lot-matched repair stock — tile manufacturers re-run designs but colors shift slightly between production runs, so future repairs from a fresh batch may not match.

Centering: tile patterns typically center on the room's main axis or focal point so cuts at opposing edges are symmetrical. Starting from one wall and tiling outward usually produces an awkwardly thin tile at the opposite wall — visually obvious. Plan the layout dry on the floor (or with chalk lines) before committing to mortar.

Diagonal vs. straight: diagonal (45°) layouts make rooms feel larger and break up the gridded look but require 15–20% more tile because corner cuts are wasted. Straight layouts (parallel to walls) are more efficient and easier to install.

Grout lines: tile size and spacing affect both the visual scale and how forgiving the layout is. Larger tiles (24-inch or larger) need flatter floors — variations over 1/8 inch in a 10-foot span produce tile lippage (one corner higher than the adjacent) that's both visible and a trip hazard.

Most installations require cut tiles at perimeter walls and around fixtures. The fewer those cuts, the less waste — adjusting tile size or layout origin to minimize cuts saves both materials and labor. A room exactly 12 feet wide tiled in 12-inch tiles wastes nothing on the cuts; a room 11 feet 6 inches wide tiled with the same tiles wastes substantial material in the perimeter cut row.

Around toilets, vanities, and other fixtures, cuts produce small pieces of tile that often can't be used elsewhere — they go to waste. The 15% waste recommendation for rooms with fixtures isn't conservative; it's realistic.

Tile installations fail mostly because the subfloor moves — wood subfloors flex, tile is rigid, and the bond between them cracks at grout lines or pops tiles loose. The TCNA (Tile Council of North America) handbook specifies underlayment requirements: cement board, uncoupling membrane (e.g., Schluter Ditra), or properly installed cementitious self-leveling — depending on the substrate.

On concrete, cracks can telegraph through to the tile if not isolated with a crack-isolation membrane. On wood subfloors, deflection over a 10-foot span should be under L/360 (about 1/3 inch per 10 feet) for standard ceramic, L/720 for natural stone. Calculators don't tell you this, but the labor and material cost of a tile job that fails in 3 years far exceeds any savings from cutting corners on substrate prep.