★ REFERENCE CHART · CONSTRUCTION · TILE
For a 100 sq ft room tiled in 12×24 inch tiles with 10% waste, you need 110.0 sq ft of tile: 55 tiles, so buy 6 boxes (60 tiles, covering 120 sq ft). The chart below gives square feet per tile for 8 common sizes; the calculator turns your room into a box count.
Tile shopping goes wrong in one place: people divide the room area by the tile area and buy exactly that many tiles, with nothing left for cuts, breakage, or a future repair. This calculator adds a waste allowance first, then rounds boxes up, so you leave the store with spares instead of a half-finished floor.
Square feet per tile is the tile's nominal area: length × width, divided by 144. A 12×24 inch tile is 288 square inches, which is 2.00 sq ft. Grout joints make the laid area per tile slightly larger, and cuts make it smaller; the waste allowance absorbs both effects, which is why the calculator works from nominal area.
| Tile size | Sq ft per tile | Tiles per 100 sq ft (before waste) | Common uses |
|---|---|---|---|
| Subway 3×6 in | 0.125 | 800 | Kitchen backsplashes, shower walls |
| 4×4 in | 0.111 | 900 | Small bathrooms, accent walls |
| 6×6 in | 0.25 | 400 | Bathroom floors and walls |
| 12×12 in | 1.00 | 100 | Bathroom and kitchen floors |
| 12×24 in | 2.00 | 50 | Modern floors, large bathrooms |
| 18×18 in | 2.25 | 45 | Large rooms, open-plan floors |
| Plank 6×36 in | 1.50 | 67 | Wood-look floors, hallways |
| 24×24 in | 4.00 | 25 | Large-format floors, commercial spaces |
Setup: 100 sq ft, 12×24 inch tiles at 2.00 sq ft each, 10% waste, 10 tiles per box.
Line 1 — needed area. 100 × 1.10 = 110.0 sq ft.
Line 2 — tiles. 110.0 ÷ 2.00 = 55 tiles.
Line 3 — boxes, rounded up. 55 ÷ 10 = 5.5, rounded up to 6 boxes (60 tiles, covering 120 sq ft).
(A) 100 sq ft in 12×12 tiles, 10% waste. Needed area is still 110.0 sq ft, but each tile covers 1.00 sq ft, so you need 110 tiles and 11 boxes of 10.
(B) 200 sq ft in 24×24 tiles, 10% waste. Needed area is 220.0 sq ft; at 4.00 sq ft per tile that is 55 tiles and 6 boxes of 10.
(C) 100 sq ft in 12×24 tiles, 0% waste. Needed area is 100.0 sq ft, which is 50 tiles and 5 boxes — but with no spare for a single broken tile, this is a risky buy, not a saving.
| Output | Formula | What it means |
|---|---|---|
| Needed area | Room area × (1 + waste %) | 110.0 sq ft at the defaults — the room plus room for cuts and breakage. |
| Tiles needed | Needed area ÷ sq ft per tile | 55 tiles at the defaults. |
| Boxes to buy | Tiles needed ÷ tiles per box, rounded UP | 6 boxes at the defaults — always rounded up, never down. |
| Area covered | Boxes × tiles per box × sq ft per tile | 120.0 sq ft at the defaults — the spare 10 sq ft is your repair stock. |
The calculator uses nominal tile area: the printed size on the box. Real tiles vary slightly by batch, and grout joints add a small amount of laid area per tile, while cuts around edges, pipes, and corners consume tile. The waste allowance is the single number that covers all three effects, which is why a straight-lay rectangle needs 10% but a diagonal layout, a herringbone pattern, or a room full of obstacles needs 15% or more. Always round boxes up: a shortfall of one tile means a second trip, a second dye lot, and a visible mismatch. Keep at least one spare box after the job for future repairs.
Bright Side Kit. "Tile Size Chart & Coverage Calculator." https://brightoolbox.com/tile-size-chart/ Accessed October 24, 2026.2.00 sq ft. A 12×24 inch tile is 288 square inches, and 288 ÷ 144 = 2.00 sq ft. Fifty of them cover 100 sq ft before waste.
It depends on the tile size. At 10% waste you need 110.0 sq ft of tile: 55 tiles in 12×24, 110 tiles in 12×12, and 880 tiles in subway 3×6. The calculator does the division for your size.
10% for a straight-lay rectangle, 15% or more for diagonal layouts, herringbone, or rooms with many obstacles. Waste covers cuts, breakage, and spares — never buy with 0% unless you enjoy a second trip.
Always up. You cannot buy part of a box, and a shortfall of one tile means a second trip and possibly a different dye lot. The calculator always rounds boxes up.
Only slightly, and the waste allowance covers it. Wider grout joints add a little laid area per tile, but cuts consume far more. That is why this calculator works from nominal tile area plus waste.
55 tiles at 10% waste, or 6 boxes of 10. Needed area is 220.0 sq ft, and each 24×24 tile covers 4.00 sq ft.
Because dye lots change. A cracked tile replaced from the same batch matches; one bought a year later may not. One spare box is cheap insurance for the life of the floor.