How much wastage allowance should I add for tiles?

A 10% wastage allowance is standard for straightforward rectangular rooms with tiles laid in a grid pattern. Increase to 15% for diagonal layouts, complex room shapes, or large-format tiles that require more cuts. For natural stone tiles which are more prone to breakage, 15-20% is advisable.

Does tile size affect how many I need?

Larger tiles cover more area per tile, so fewer are needed. However, larger tiles also mean more waste per cut. A 600x600mm tile has four times the area of a 300x300mm tile, but any off-cut waste is proportionally larger. For small or complex rooms, smaller tiles can actually be more economical.

Should I account for grout spacing?

This calculator gives results based on tile face dimensions, which is standard practice. Grout joints (typically 2-5mm) are small enough that the wastage allowance comfortably covers any difference. For very large areas or narrow grout joints, the effect is negligible.

Tile Calculator

Calculate tiles needed with wastage allowance

Tiling a floor, wall, or splashback requires careful material estimation. Tiles are sold in boxes of fixed quantities, and running short mid-project is particularly problematic -- the same tile from a different production batch may have subtle colour variations that are visible once laid. Conversely, buying far too many tiles wastes money on a product that is difficult to return once opened. The key to accurate tile estimation is understanding wastage. Every tiling project generates waste from cuts at edges and corners, breakages during cutting, and the occasional defective tile in a box. The wastage percentage varies depending on the tile layout pattern, room complexity, and tile material. Ceramic tiles cut cleanly and generate less waste, while natural stone and porcelain are more prone to snapping during cuts. This calculator works with any tile size, from small mosaic tiles to large-format porcelain slabs, and allows you to adjust the wastage percentage to match your specific project requirements.

How to Use This Calculator

To calculate how many tiles you need: 1. Enter the area length in metres. For a floor, measure the longest dimension of the room. For a wall, measure the width of the wall. 2. Enter the area width in metres. For a floor, measure the perpendicular dimension. For a wall, measure the height to be tiled. 3. Enter the tile dimensions in centimetres. Measure the face of the tile, not including any spacer lugs. Common UK sizes include 30x30cm, 45x45cm, 60x30cm, and 60x60cm. 4. Adjust the wastage allowance using the slider. The default 10% is suitable for rectangular rooms with a grid layout. Increase to 15-20% for diagonal layouts, L-shaped rooms, or natural stone tiles. 5. Review the results. The highlighted figure is the number of tiles to purchase (including wastage). The exact tile count, total area, and number of extra tiles for wastage are also shown.

How It Works

The tile calculation divides the total area by the area of a single tile, then adds wastage: Area to tile (m2) = length (m) x width (m) Tile area (m2) = (tile length in cm / 100) x (tile width in cm / 100) Tiles needed (exact) = ceil(area / tile area). This is rounded up because you cannot buy partial tiles. Tiles with wastage = ceil(tiles needed x (1 + wastage % / 100)) For example, a 3m x 2m floor (6 m2) with 30x30cm tiles (0.09 m2 each): tiles needed = ceil(6 / 0.09) = 67 tiles. With 10% wastage: ceil(67 x 1.10) = 74 tiles. The extra 7 tiles account for edge cuts, breakages, and spares. The wastage allowance covers: partial tiles at room edges (the largest source of waste), breakages during cutting, occasional manufacturing defects, and a small reserve for future repairs.

When ordering tiles, check how many tiles come in each box and round up to whole boxes. Most tile retailers will accept returns of unopened boxes, so ordering one extra box is good practice. For floors, buy adhesive at approximately 4-5 kg per square metre and grout at 0.5-1 kg per square metre (varies with tile size and joint width). Large-format tiles (600mm and above) generally require a notched trowel with 10-12mm teeth and may need back-buttering for full adhesion coverage.