Tile Calculator — How Many Tiles Do I Need?
A tile calculator converts the area you want to cover into the number of tiles to buy. The math is straightforward: divide the surface area (length × width) by the area of one tile, then add a waste allowance for cuts, breakage, and future repairs. Because tile dimensions are usually given in centimeters or inches while rooms are measured in meters or feet, the calculator handles the unit conversion and rounds the result up to whole tiles and full boxes.
The waste factor is the step most people skip — and the reason projects run short. A common allowance is around 10% for straight layouts, 15% or more for diagonal or herringbone patterns, and extra for rooms with many corners, columns, or niches. Buying the full amount in one order also matters because tiles from different production batches can vary slightly in shade and caliber. Always confirm quantities with your installer before purchasing.
How it works
Area to cover = Length × Width. Tile area = tile width × tile height (converted to the same unit). Tiles needed = ⌈(Area ÷ Tile area) × (1 + waste%)⌉. Boxes = ⌈Tiles needed ÷ tiles per box⌉. Typical waste: 10% straight lay, 15%+ diagonal patterns.
Use cases
- Working out how many boxes of porcelain tile to buy for a living room floor
- Estimating wall tiles for a bathroom or kitchen backsplash, including cuts
- Comparing total cost between tile sizes (e.g. 60×60 cm vs 80×80 cm) for the same area
- Adding the right waste percentage for a diagonal or herringbone layout
- Budgeting material for a multi-room renovation by summing several areas
- Checking a contractor's material list before approving the purchase
Frequently asked questions
How do I calculate how many tiles I need?
Multiply the room's length by its width to get the area, then divide by the area of a single tile expressed in the same unit. For example, a 4 × 5 m room (20 m²) with 60 × 60 cm tiles (0.36 m² each) needs 20 ÷ 0.36 ≈ 55.6, rounded up to 56 tiles. Add a waste allowance of about 10% — 62 tiles — before converting to boxes.
How much extra tile should I buy for waste?
A practical rule is 10% extra for a standard straight layout and 15% or more for diagonal, herringbone, or other patterns that require many cuts. Rooms with lots of corners, pipes, or niches also increase waste. Keeping a few spare tiles after the job is finished is useful for future repairs, since matching the exact shade later can be difficult.
How many 60x60 tiles do I need per square meter?
A 60 × 60 cm tile covers 0.36 m², so you need about 2.78 tiles per square meter before waste. For comparison, 45 × 45 cm tiles cover 0.2025 m² (about 4.94 per m²) and 80 × 80 cm tiles cover 0.64 m² (about 1.56 per m²). Multiply the rate by your total area and round up to whole tiles.
Do I need to subtract doors and windows from the area?
For floors, subtract only large fixed obstacles such as kitchen islands or built-in cabinets that will not be tiled underneath. For walls, subtract the area of doors and windows, but be conservative — the cuts around openings generate extra waste that partially offsets the subtracted area. When in doubt, subtract openings and keep the standard 10–15% waste factor.
Does grout spacing change the number of tiles needed?
Slightly. Grout joints of 2–5 mm effectively increase the area each tile occupies, reducing the count by roughly 1–2% in most formats. For most projects this difference is smaller than the waste allowance, so the standard calculation with a 10% margin already covers it. For very small mosaics or very wide joints, add the joint width to the tile dimensions for a more precise count.