Tile Calculator

Work out the area to be tiled in square feet, then divide by the area of a single tile in square feet. A 12-by-12-inch tile is exactly one square foot, so a 60 square foot floor needs 60 tiles before waste. For other sizes, multiply the tile's width and height in inches and divide by 144 to get its square footage — a 12-by-24-inch tile is 288 divided by 144, which is 2 square feet.

Ten percent is standard for a straight grid layout. Go to 15 percent for a diagonal layout, which cuts a triangle off every perimeter tile, and for herringbone or other patterns needing precise alignment. Add more again for rooms with many corners, alcoves, or fixtures to cut around. Breakage during cutting is normal, and one cracked tile with no spare stops the job.

Grout use depends on tile size, joint width, and tile thickness. Larger tiles need less grout per square foot because there are fewer joints in the same area, while wider joints use more. This calculator estimates pounds of grout from all four variables. Buy the next whole bag up, since grout is sold in 10 and 25 pound bags and a partial batch mixed days later will not colour-match the first.

For rectified porcelain with precisely cut edges, 1/16 to 1/8 inch is typical. For standard ceramic or natural stone with slight size variation between tiles, 1/8 to 3/16 inch gives you room to keep the lines straight. Anything at or above 1/8 inch generally requires sanded grout, while narrower joints need unsanded, which shrinks less in a thin line.

In a bathroom, tile usually runs under a freestanding vanity but stops at a built-in one, so decide before you measure. In a kitchen, tile typically runs under the dishwasher and range so appliances can be pulled out for service without catching on a lip. When in doubt, include the area — a few extra tiles cost far less than discovering a bare patch when an appliance comes out.

Almost always by the box. Tile is sold in cartons of a fixed count, and suppliers rarely break them. More importantly, tiles are produced in batches with a shade code printed on the carton, and mixing lots gives a visible colour shift across the finished floor. Buy all your tile at once from the same shade lot, spares included.