Plan a floor, backsplash, or shower wall in one pass. Add each rectangle of the room, choose the tile size and grout joint, and pick the layout — straight, diagonal, or herringbone — to set a realistic waste allowance. The calculator returns the tile count and boxes, the grout in pounds or kilograms using the MAPEI consumption formula, and thinset bags by trowel size from published manufacturer coverage. Works in inches and feet or centimeters and meters.
Tiling a bathroom? The paint calculator handles the walls above the tile, and the drywall calculator estimates board for any walls you replace. Pricing the whole job for a client? Drop the numbers into the construction estimate generator.
Frequently asked questions
How many tiles do I need?
Multiply the floor or wall area by one plus your waste allowance, then divide by the area each tile covers including one grout joint. For 100 sq ft of 12×12 in tile with 1/8 in joints and 10 % waste, each tile covers 12.125 × 12.125 in, or about 1.02 sq ft, so you need 108 tiles. Then divide by the tiles per box and round up. Always round up to whole boxes and buy them all from the same lot number so the shade matches.
How much extra tile should I buy for waste?
Plan on about 10 % for a straight or grid layout in a simple rectangular room, 15 % for a diagonal layout, and 15–20 % for herringbone or chevron, because those patterns cut a piece off nearly every tile at the edges. Add a little more for small rooms with lots of corners, large-format tile that breaks expensively, or natural stone with color variation you may want to sort. Keep a few leftover tiles for future repairs — discontinued tile is very hard to match.
How is the grout amount calculated?
We use the formula MAPEI publishes for its grout calculator: kg per m² = (A + B) ÷ (A × B) × C × D × 1.6, where A and B are the tile length and width, C is the joint width, and D is the joint depth (roughly the tile thickness), all in millimeters, and 1.6 kg/L is the average density of cement grout. We add 10 % for mixing and cleanup. Small tiles and wide joints need far more grout: a 2×2 in mosaic uses several times as much as 12×12 in tile.
How much thinset do I need, and which trowel?
Thinset coverage depends on the trowel notch. For a 50 lb bag, Custom Building Products' VersaBond data sheet lists 85–95 sq ft with a 1/4 × 1/4 in square notch and 60–67 sq ft with a 1/4 × 3/8 in notch; retailer charts give about 90–100 sq ft for a 3/16 in V-notch and 40–50 sq ft for a 1/2 in notch. We use the low end. As a rule of thumb, mosaics take a V-notch, tiles up to 8 in a 1/4 in square notch, up to about 15 in a 1/4 × 3/8, and larger tiles a 1/2 in notch — but check coverage by pulling up a tile.
Does the grout joint width change the tile count?
Slightly. Each tile effectively occupies its own size plus one joint, so wider joints mean fewer tiles. For large tile the difference is small — 1/8 in joints on 12×12 tile reduce the count by about 2 %. For small tile it adds up: 1/8 in joints on 2×2 mosaic reduce it by about 11 %. The calculator includes the joint automatically, so enter the spacer size you plan to use. Rectified porcelain can go as tight as 1/16 in; hand-made and non-rectified tile usually needs 1/8 in or wider to hide size variation.