Tile Calculator
Calculate how many boxes of tiles you need for floors or walls — with waste included — for any rectangular surface.
What this calculates
Calculates the net area, area with waste allowance and total number of boxes needed to tile a rectangular surface.
Formula used
Area = length × width. Area with waste = area × (1 + waste %). Boxes = area with waste ÷ m² per box (rounded up).
Worked example
A room of 4 m × 3 m has 12 m². With 10% waste: 13.2 m². If each box covers 2 m², you need 7 boxes.
Typical waste allowances
Straight lay: 10%. Diagonal (45°): 15%. Rooms with many cuts or irregular shapes: 15–20%. Always buy extra boxes from the same production lot to match color and texture.
When not to use this calculator
For rooms with curved walls, multiple alcoves or complex patterns, increase the waste percentage manually. This calculator assumes a simple rectangular surface.
Frequently asked questions
How many tiles do I need per m²?
It depends on the tile size. Check the coverage per box on the product label and enter that value in the field above.
How much waste should I add?
10% for straight lay, 15% for diagonal. Add more for irregular rooms or many cuts.
How many m² are in a box?
Typically 1.5–2.5 m². Check the product label for the exact coverage per box.
Do I need adhesive?
Yes. Tile adhesive (thinset) and grout are needed. Coverage per bag varies — check the manufacturer specs.
Assumptions
- Boxes are rounded up to the nearest whole box.
- Waste is applied to the net area.
- Does not include adhesive, grout or tile spacers.
- Valid for simple rectangular surfaces only.
Wet areas (showers, pool surrounds) require waterproofing membranes, suitable tile adhesives and proper grout. Always follow manufacturer specifications.
Common mistakes
- Buying tiles from different production lots (color mismatch).
- Not checking whether the surface is flat and plumb before tiling.
- Underestimating waste for diagonal or complex patterns.