THE BASICS
1. Measuring the area
Multiply length by width for each area and add them up: a 10 × 10 ft bathroom floor is 100 sq ft. For L-shaped rooms, split into rectangles and sum — tile gets cut in the field, so inch-level precision is not required.
Don't subtract floor openings the way you do for walls: the floor gets fully covered, and the cuts around the toilet flange or vanity are exactly what the waste factor absorbs.
FIGURES
2. What each box of tile covers
Tile doesn't come loose: it ships in boxes with a fixed coverage that depends on the format. A 12×12 box typically holds 10 pieces (≈ 10 sq ft); a 12×24 box holds 8 pieces (≈ 16 sq ft). Large formats cover more per box but demand a higher waste factor.
| Format | Pieces per box | Coverage per box | Boxes for 100 sq ft |
|---|---|---|---|
| 12 × 12 in | 10 | ≈ 10.0 sq ft | 11 |
| 12 × 24 in | 8 | ≈ 16.0 sq ft | 7 |
| 16 × 16 in | 5 | ≈ 8.9 sq ft | 13 |
| 18 × 18 in | 5 | ≈ 11.3 sq ft | 10 |
Reference coverage for common formats; your exact box coverage is printed on the label.
CRITERIA
3. The waste factor: 10% is the standard
Always add a margin over the net area: 10% for straight-lay patterns in small and mid formats, 15% for large formats (18×18 up), diagonal layouts, or rooms with lots of cuts around cabinets and flanges.
The leftover isn't waste — keep a closed box for future repairs. Chipping a piece at the wet saw is normal, and factory culls happen in every batch.
SHOPPING
4. How many boxes to buy: the formula
Area with waste divided by the box coverage, rounded up: (area × 1.1) ÷ sq ft per box. A 100 sq ft floor with 12×12 tile is (100 × 1.1) ÷ 10 = 11 boxes.
If your format isn't listed, check the box label: coverage in sq ft is printed on it, and the formula stays the same.
Ready to skip the math?
Calculate tile for my project