Tile Calculator
Count the tiles a floor or wall needs from the area, tile size and grout gap, with a cutting allowance and the number of boxes.
How many tiles and boxes for the area.
How the tile calculator works
Each tile plus its grout joint covers (tile length + gap) × (tile width + gap). Divide the area by that, add a cutting allowance — 10% for a plain layout, 15% for diagonal or patterned layouts and rooms with many corners — and round up. Divide by the tiles per box to get boxes.
Measure the area at its widest points; alcoves and returns need full tiles cut down, which is what the allowance covers.
Formula: tiles = area ÷ ((tile length + gap) × (tile width + gap)) × (1 + waste)
Worked examples
| Inputs | Tiles to buy | Note |
|---|---|---|
| 4 × 3 m, 300 mm tiles, 3 mm gap | 144 | 144 tiles |
| 4 × 3 m, 600 × 300 mm tiles | 73 | 73 tiles |
| 13 × 10 ft, 12 in tiles, ⅛ in gap | 141 | 141 tiles |
FAQFrequently asked questions
How much extra should I buy for cuts?
10% for a straight layout in a simple room; 15% for diagonal or herringbone patterns, or rooms with many corners. Keep a few spares for future repairs — batches vary in shade.
What grout gap should I use?
2–3 mm for rectified porcelain, 3–5 mm for standard ceramic floor tiles, 1.5–3 mm for wall tiles. Wider joints hide small size variations.
Do large tiles need fewer boxes?
Fewer tiles, but often more waste per cut, so use the higher allowance. Check the box coverage in square meters as well as the count.
How do I tile a room that is not rectangular?
Split it into rectangles, run the calculator for each and pin the results, or measure the total area and enter it as length × 1.
Where these figures come from
- The Engineering ToolBox — material densities, coverage and unit data — bulk densities, concrete at 2,400 kg/m³, board and sheet sizes
- Gypsum Association — gypsum board sizes — 4 × 8 and 4 × 12 ft sheets
- ADA Standards for Accessible Design — ramps (§405) — maximum running slope 1:12
- International Code Council — the International Residential Code
Last checked: September 2026. Coverage rates and material sizes are typical manufacturer figures — check the product you buy.