Tile Calculator guide
Tile Calculator: How Many Tiles Do I Need?
Use our tile calculator to work out how many floor or wall tiles and boxes you need, with grout gaps and extra for cuts and waste.
By the AllCalculator editorial teamUpdated 16 October 20261 min read
Buying too few tiles means a second trip and a risk of mismatched batches; buying too many wastes money. Our Tile Calculator gets it right.
How to use the calculator (Tile Calculator)
- Enter the length and width of the area to tile.
- Enter the tile size in millimetres and your grout gap.
- Enter tiles per box and the price per box if you know them.
- Set how much extra to allow for cuts and waste.
How it works
- Tiles per m² = 1 ÷ ((tile width + gap) × (tile height + gap)), in metres
- Tiles needed = area × tiles per m², plus extra for waste
- Boxes = tiles ÷ tiles per box, rounded up
How much extra?
| Layout | Allow extra |
|---|---|
| Straight lay, simple room | 10% |
| Lots of cuts or obstacles | 15% |
| Diagonal or herringbone | 15–20% |
A worked example
With the calculator's default settings, an area of 3m × 2.5m (7.5m²) with 300 × 600mm tiles and a 3mm gap needs about 41 tiles, or 46 with 10% extra. At 6 tiles a box, that's 8 boxes.
Frequently asked questions
Should I keep spare tiles?
Yes. Keep a few in case one cracks later, as the same batch may be hard to find.
How much adhesive do I need?
Roughly 4 to 6kg per m², depending on the tile size and trowel. Check the bag.
Can I tile over old tiles?
Sometimes, if they're firmly fixed and the surface can take the weight. Check with the adhesive manufacturer.
To work out an area in square feet, use our Square Footage Calculator.
Sources and further reading
Links open official and independent websites in a new tab.
This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.