✓Convert the tile dimensions and the project dimensions into compatible units before dividing.
✓Add waste after calculating the base tile count, not by guessing extra boxes.
✓Buy complete boxes and confirm the exact tile count or coverage printed on the box.
Tile area = tile length × tile widthBase tile count = project area ÷ tile areaPurchase tile count = base tile count × (1 + waste allowance)Boxes = purchase tile count ÷ tiles per box, rounded up 1. Measure each tiled surface separately
For a rectangular floor, multiply length by width. For walls, showers or backsplashes, calculate each surface independently and subtract large openings that will not receive tile.
Separate surfaces are useful because wall tile and floor tile may use different products, sizes or waste assumptions.
2. Calculate the coverage of one tile
A 12 in × 12 in tile covers one square foot, but many common tile sizes do not convert so neatly. Convert inches to feet—or millimetres to metres—before calculating tile area.
Nominal tile dimensions can differ slightly from actual dimensions. For purchasing, the manufacturer's box coverage is often the most practical final reference.
3. Choose waste based on the layout
Straight layouts with a simple room shape generally produce fewer offcuts than diagonal patterns, herringbone layouts or rooms with many corners. Large-format tile can also create expensive offcuts when a partial tile cannot be reused elsewhere.
Waste is not a substitute for measuring carefully. It is a buffer for the unavoidable losses that remain after a good layout plan.
4. Round up to full boxes
Retail tile is normally purchased by the box. Once the waste-adjusted tile count or coverage is known, divide by the quantity in each box and round up.
Keeping a few matching spare tiles after installation can be useful because the same color lot or product line may not be available later.
Example: 12 ft × 12 ft room with 12 in × 12 in tile
- Room area
- 144 sq ft
- Tile area
- 1 sq ft
- Waste allowance
- 10%
- Tiles per box
- 10
The base quantity is 144 tiles. With 10% waste the planning quantity is 158.4 tiles, which rounds to 159 tiles. At 10 tiles per box, that requires 16 full boxes.
Run your own numbers in the Tile Calculator →What to avoid
- Mixing inches and feet in the same calculation
- Ignoring pattern or cut waste
- Rounding tile count before adding waste
- Dividing by box coverage and then rounding down
Before you order
- Measure every tiled surface
- Confirm tile dimensions
- Choose layout
- Set waste allowance
- Check tiles or coverage per box
- Round to full boxes