Tile Calculator
Work out how many tiles and boxes to buy for any floor or wall. Pick a tile size, enter the area and choose your layout.
100 ft² of 12×12 in tile needs 110 tiles with 10% extra; 12×24 in tile needs 55.
ft² · ft² with extra · ft² per tile
Cost is tile only, at your price per square foot including the extra. For several areas, grout, thinset and a drawing, open the flooring calculator for tile.
Tiles per 100 square feet
| Tile size | Covers per tile | Exact (no joint) | +10% (straight) | +15% (diagonal) |
|---|---|---|---|---|
| 12 × 12 in | 1.000 ft² | 100 | 110 | 115 |
| 12 × 24 in | 2.000 ft² | 50 | 55 | 58 |
| 18 × 18 in | 2.250 ft² | 45 | 49 | 52 |
| 24 × 24 in | 4.000 ft² | 25 | 28 | 29 |
| 6 × 24 in | 1.000 ft² | 100 | 110 | 115 |
| 3 × 6 in | 0.125 ft² | 800 | 880 | 920 |
Joint width ignored in this table, which slightly overestimates. Round up to whole boxes.
Tile calculators
Floor tile calculator
Several areas, layout pattern, grout joint, boxes, cost and a drawing of your floor.
Backsplash calculator
Kitchen backsplash between counter and cabinets, minus windows and outlets.
Shower & wall tile calculator
Walls, niches and shower surrounds, wall by wall.
Grout calculator
Pounds of grout from tile size, joint width and depth.
Thinset calculator
Bags of thinset mortar by trowel size and area.
Tile installation cost
Material plus your local labor rate per square foot.
Grout, thinset and cost
Tiles are only part of the shopping list. Grout depends on joint width and tile size: 100 ft² of 12×12 in tile with 1/8 in joints takes about 6.8 lb of grout, while 3×6 in subway tile with 1/16 in joints takes about 10.3 lb. Thinset is spread under every tile: one 50 lb bag covers roughly 85 ft² with a 1/4 × 1/4 in trowel and 60 ft² with a 1/4 × 3/8 in trowel used for larger tiles.
For the total budget, multiply the area with extra by the price per square foot; a 100 ft² floor with 10% extra at $3.50 per ft² is $385 in tile before grout, thinset and labor. The flooring calculator for tile works out grout, thinset and cost for your exact floor.
Waste allowance by layout
| Layout | Typical extra | Why |
|---|---|---|
| Straight (grid) | 10% | Cuts only along two walls |
| Brick / offset | 10% | Offsets create a cut at each row end |
| Diagonal | 15% | Triangular cuts along every wall |
| Herringbone | 15% | Angled cuts at every edge, many small offcuts |
How to calculate tiles
- Measure the area. Measure length and width in feet. For L-shaped rooms, split into rectangles and add them.
- Find the tile coverage. Multiply tile width by length in inches and divide by 144 for square feet. Add the joint width to each side for a more exact count.
- Add extra for cuts. Multiply the area by 1.10 for straight layouts or 1.15 for diagonal and herringbone.
- Divide and round up. Area with extra ÷ coverage per tile = tiles. Round up, then divide by tiles per box and round up again.
Tiles = ⌈ area (ft²) × (1 + extra) ÷ ((W + joint) × (L + joint) ÷ 144) ⌉
Questions
How many tiles do I need for 100 square feet?
With 12×12 in tiles, 100 ft² plus 10% extra is 110 tiles. With 12×24 in tiles it is 55, and with 24×24 in tiles 28.
How much extra tile should I buy?
About 10% for a straight or brick layout and about 15% for diagonal or herringbone, where more tiles are cut at the edges. Add a little more for small rooms with many corners, and keep a box for future repairs.
Does the grout joint change the tile count?
Slightly. Each joint adds to the area one tile covers. For 12×12 in tiles with 1/8 in joints, one tile covers 1.021 ft² instead of 1 ft², about 2% fewer tiles. Many calculators ignore it, which errs on the safe side.
How do I calculate tiles for an L-shaped room?
Split the room into rectangles, measure each one, and add the areas together. The floor tile calculator lets you add several areas and does the sum for you.
How many boxes of tile do I need?
Divide the tile count by the number of tiles per box, or divide the area (with extra) by the square feet per box printed on the carton, and round up.
Waste allowances reflect common installer practice; your installer or the tile maker may recommend more for large-format or patterned tile. Calculations last checked 2026-11.