Tile Calculator
Work out how many tiles and boxes to buy for a floor or wall, plus the grout and adhesive you will need.
How the calculator works
- Net area:
length × width − deductions - Tiles:
net area ÷ ((tile length + joint) × (tile width + joint)), then plus wastage, rounded up - Boxes: tiles ÷ tiles per box, rounded up
- Grout:
((L + W) ÷ (L × W)) × thickness × joint × 1.6kg per m², with L, W, thickness and joint in mm - Adhesive: about 4.5 kg per m² for a 6 mm notched trowel bed
Worked example: 4 m × 3 m floor with 600 × 600 mm tiles
- Area: 4 × 3 = 12 m²
- Tile footprint with a 3 mm joint: 0.603 × 0.603 = 0.3636 m²
- Tiles: 12 ÷ 0.3636 = 33.0, or 36.3 with 10% wastage, so 37 tiles
- Boxes of 4: 10 boxes (40 tiles)
- Grout (10 mm tile, 3 mm joint): 0.16 kg/m² × 12 = about 1.9 kg
- Adhesive: 4.5 × 12 = 54 kg, or 3 bags of 20 kg
Wastage guide
| Layout | Suggested wastage |
|---|---|
| Straight lay, simple rectangular room | 7-10% |
| Diagonal or herringbone | 12-15% |
| Large-format tiles (600 mm and up) or many cuts | 10-15% |
| Small, irregular rooms, stairs | 15-20% |
Frequently asked questions
How many tiles do I need per square metre?
Divide 1 by the tile area including the joint. A 600 × 600 mm tile with a 3 mm joint needs about 2.75 tiles per m², and a 300 × 300 mm tile needs about 10.8.
Why add wastage?
Cuts at edges, breakage and mis-cuts all use tiles. Buying a few extra also covers future repairs, since a later batch of the same tile can vary in shade.
Do I need to buy whole boxes?
Yes, tiles are sold by the box, so the calculator rounds up. Buy all boxes from the same batch number to keep colour consistent.
Does the adhesive figure depend on tile size?
Yes. Large tiles need a deeper notched trowel and more adhesive, up to 6 kg/m² or more. Follow the adhesive manufacturer's coverage chart.
Can I use this for wall tiles?
Yes. Enter the wall height as the length and the wall width as the width, and deduct windows or fittings in the deduction field.
