How it's calculated
Each tile on a floor or wall takes up its own size plus one grout joint along two of its edges. The calculator works out that footprint, divides the area to tile by it, adds a percentage for cuts, breakage and spares, and rounds up to whole tiles and whole boxes.
Daltile recommends buying approximately 10% more tile than you expect to need, kept as "attic stock" so that a cracked tile can later be replaced from the same dye lot Daltile. That is the default extra. Diagonal and herringbone layouts, small rooms with many cuts and large-format tiles all waste more, so raise it for those.
The formula
- Area to tile = length × width, converted to square inches (sq ft × 144) or square millimeters (m² × 1,000,000).
- Tile footprint = (tile length + joint) × (tile width + joint).
- Tiles to cover = area ÷ tile footprint.
- Tiles to buy = tiles to cover × (1 + extra %), rounded up.
- Boxes = tiles to buy ÷ tiles per box, rounded up. Cost = boxes × price per box.
Worked example
An 8 × 10 ft bathroom floor in 12 × 12 in tile with 1/8 in joints needs 78.36 tiles to cover the floor exactly. With 10% extra that becomes 87 tiles, or 9 boxes of 10, which costs $225 at an example $25 a box.
Tiles to buy: 87 tiles · 9 boxes
The same floor in 12 × 24 in plank tile needs 44 tiles. A 5 × 8 ft shower wall in 3 × 6 in subway tile with 1/16 in joints takes 342 tiles.
Assumptions and limitations
- Full field tile only. Bullnose, trim pieces, mosaics on mesh sheets and decorative borders are counted separately.
- Rectangular areas. For L-shaped rooms or walls with a window, work out the area with the square footage calculator, then size it here as an equivalent rectangle, or subtract the opening yourself.
- Nominal sizes. Use the actual tile dimensions from the box if they differ from the nominal size, and the joint width your installer will use.
- Thinset, grout and backer board are not included. Their coverage depends on the trowel notch, joint size and product; check the bag.
- Tiles per box is on the box. The default of 10 is only an example.
- Prices are examples. Enter your own.
For laminate or vinyl plank instead of tile, use the flooring calculator.