Tile Calculator
Calculate floor or wall tile quantity from room dimensions and tile size. Includes waste, box count and a cost estimate.
Tiles needed
132
- Floor area
- 120 sq ft
- Area with waste
- 132 sq ft
- Tile size
- 12 × 12 in
- Boxes needed
- 14
- Estimated tile cost
- $490.00
Add 10% waste for a straight layout and 15% for diagonal or herringbone patterns. Confirm the square footage printed on the box before ordering.
Tile is sold by the box, but the box coverage changes with tile size, pattern and manufacturer. This calculator starts from your room dimensions, adds a waste allowance, and converts the result into both individual tiles and boxes.
Use 10% waste for a straight lay and 15% for diagonal, herringbone or rooms with many cuts. Keep at least one spare box for future repairs; dye lots change and matching a discontinued tile is difficult.
How the tile calculator works
Floor area = length × width. Multiply by (1 + waste %) to get the area you should buy. Tile area = tile width × tile height, converted to square feet. Tiles needed = area with waste ÷ tile area, rounded up. Boxes = area with waste ÷ box coverage, rounded up.
Worked example
A 10 × 12 ft room is 120 sq ft. With 10% waste you need 132 sq ft. Twelve-inch square tiles cover 1 sq ft each, so that is 132 tiles. At 10 sq ft per box, buy 14 boxes.
How to measure for tile
- Measure the length and width of the floor at the widest points. For an L-shaped room, split it into rectangles.
- Measure wall tile from the finished floor to the ceiling, then subtract the tub, shower or backsplash areas you are not tiling.
- Check the square footage printed on the tile box; it is more reliable than counting tiles.
- Add 10% for a straight lay and 15% for diagonal, herringbone or rooms with many cuts.
- Buy all tile in one order so the dye lot matches, and keep at least one spare box.
Layout patterns and waste
| Pattern | Typical waste | Notes |
|---|---|---|
| Straight / grid | 10% | Fewest cuts; easiest layout |
| Running bond | 10% | Offset rows; still efficient |
| Diagonal | 15% | More perimeter cuts |
| Herringbone | 15% | Many angled cuts; plan the layout |
| Large format | 10–15% | Heavy; needs a flat substrate |
Common tile mistakes
- Measuring only the floor when the project also includes walls or a shower niche.
- Ordering exactly the calculated area with no waste or spare.
- Skipping a deflection check on wood subfloors before installing large tile.
- Using the wrong thin-set for the tile type or substrate.
- Grouting before the thin-set has fully cured.
Frequently asked questions
How many tiles do I need for 100 square feet?
It depends on tile size. Twelve-inch square tiles need 100 tiles plus waste, 12 × 24 inch tiles need 50, and 6 × 6 inch tiles need 400. Always add 10–15% for cuts and breakage.
How much tile waste should I allow?
Use 10% for a simple straight layout in a rectangular room, and 15% for diagonal, herringbone or rooms with closets, angles and many cuts. Buying one extra box is cheaper than delaying the job for a replacement.
How many 12 × 12 tiles are in a box?
Box coverage varies by manufacturer. A common box covers 10–15 sq ft, which is 10–15 tiles of 12 × 12 inch. Check the square footage printed on the box rather than counting tiles.
How much grout do I need?
Grout quantity depends on tile size, joint width and tile thickness. Small tiles with wide joints use much more grout than large-format tiles with 1/8 inch joints. A dedicated grout calculator is more accurate than a fixed rule.
Can I install tile over existing tile?
Sometimes, if the existing tile is well bonded, flat and the floor deflection is acceptable. Removal is safer when the old tile is cracked, loose or heavily textured. Check the substrate and use a suitable thin-set.
Should I order all tile at once?
Yes. Order the full quantity plus spares in one purchase so the tiles come from the same dye lot. Colors can vary slightly between production runs.
Assumptions and accuracy
- Dimensions are converted to feet before the calculation; 1 ft = 12 in = 0.3048 m.
- Waste allowances are estimates. Add more for irregular shapes, many cuts and uneven subgrade.
- Bag yields, coverage rates and material densities vary by product. Check the label or ask your supplier.
- Local building codes and site conditions always take precedence over a general-purpose calculator.
- Read our full methodology