Tile Calculator — How Many Tiles Do I Need?
Free tool · Works offline · Waste factor · Grout & adhesive · Metric & imperial
How to calculate how many tiles you need
The basic formula is: Room area ÷ Tile area = Number of tiles. But this gives the bare minimum — you always need more. Real rooms have cuts at edges, tiles crack during cutting, and you need spares for future repairs. The standard allowance is 10% extra for straight layouts, 15% for offset/brick bond, and 20% for diagonal or herringbone patterns. This calculator applies the correct waste factor automatically based on your chosen layout.
How many tiles for a 12×12 bathroom floor?
A 12×12 ft bathroom (3.66×3.66m = 13.4 m²) using 300×300mm tiles (0.09 m² each) needs: 13.4 ÷ 0.09 = 149 tiles base. Add 10% waste = 164 tiles. If they're sold in boxes of 10, you need 17 boxes. Always buy a complete box extra — if you need to replace a cracked tile in 5 years and the batch is discontinued, you'll be glad you kept spares.
How does grout joint size affect tile quantity?
Grout joints take up space, which slightly reduces the number of tiles needed. For standard 3mm joints the effect is minimal — less than 1%. For wider 10mm joints on large format tiles, the difference can be 3–5%. This calculator accounts for grout joint width in the tile count. Wider joints also need more grout — typically 3–5 kg/m² for standard floor tiles at 3mm joints, up to 8 kg/m² for 10mm joints.
Layout patterns — which uses the most tiles?
Straight/grid — tiles aligned in rows and columns. Least waste (10%), fastest to lay, most forgiving for beginners. Best for square rooms. Offset/brick bond — each row offset by half a tile. Slightly more waste (15%), hides imperfect room geometry well. Standard for rectangular tiles. Diagonal (45°) — tiles rotated 45°. Significant waste (20%) due to large corner cuts. Makes a room look wider. Herringbone — tiles laid in a V-pattern. 20%+ waste, time-consuming, striking result. Popular for kitchen splashbacks and hallways.
How much tile adhesive do I need?
Standard floor tile adhesive covers approximately 3–5 kg per m² for 300×300mm tiles with a 6mm notched trowel. Large format tiles (600×600mm+) need a larger notch and more adhesive — typically 5–8 kg/m². Wall tiles use less — 2–4 kg/m² with a smaller notch. Always check the adhesive manufacturer's coverage rate — it varies significantly by product and substrate. Buy 10% more than calculated to allow for waste and uneven surfaces.
Frequently asked questions
How many 600×600mm tiles for 20 m²?
Each 600×600mm tile covers 0.36 m². For 20 m²: 20 ÷ 0.36 = 56 tiles base. Add 10% = 62 tiles. If sold in boxes of 4 (1.44 m²/box), you need 16 boxes.
Should I use wall tiles or floor tiles on a floor?
Never use wall tiles on a floor — they're not rated for foot traffic and will crack. Floor tiles can be used on walls if they're not too heavy for the adhesive. Check the tile's slip resistance rating (R9 minimum for domestic floors, R11 for wet areas).
How much grout do I need for 10 m²?
For 300×300mm tiles with 3mm joints: approximately 30–50kg of grout for 10 m². The calculator's grout tab gives the exact amount based on your tile size and joint width.
Can I tile over existing tiles?
Yes, if the existing tiles are firmly bonded, flat and structurally sound. Use a flexible adhesive and check that the added weight doesn't exceed the floor/wall loading capacity. Sand or acid-etch the surface for better adhesion.