How the Bathroom Tile Calculator Works

Measure each wall you plan to tile and floor, enter dimensions along with your tile size and calculator does the rest. It converts your area into a tile count, deducts standard allowances for door and window, applies a wastage percentage based on your pattern and rounds up to full boxes.

As a quick reference for tiles per square metre, 300 x 300mm tiles need 11 per m², 600 x 300mm need 6 and 600 x 600mm need 3. Metro tiles at 200 x 100mm need 50 per m², which is why small format tiling takes so much longer to fix.

How Much Wastage to Allow

Wastage is not a maybe. Every cut at a wall edge, window reveal or pipe run produces offcuts and some tiles will break. The allowance depends mostly on your laying pattern:

• Straight grid or brick bond: 10 percent
• Diagonal layouts: 15 percent
• Herringbone and chevron: 18 percent

Bathrooms deserve top end of any range because room works against you. A bath, basin, WC, boxed in pipes and a shower enclosure force cuts on almost every course. For a straightforward bathroom allow 10 to 15 percent and for herringbone in an awkward L shaped room budget for over 20 percent.

Order everything in one go and check boxes carry same batch number. Tiles from different production batches can vary subtly in shade and the difference only becomes obvious once they are on the wall.

Choosing Bathroom Tile Sizes

Tile size changes both look and workload. Large format tiles at 600 x 600mm and above mean fewer grout lines and a cleaner look, but they need a flatter substrate and more trimming in a small room, so a compact bathroom can actually waste more with big tiles than with 300 x 300mm. Small formats and mosaics handle curves and awkward corners well at the cost of far more grouting.

For floors check the slip rating before ordering. Bathroom floors want R10 or an equivalent anti slip finish and many glossy wall tiles are neither thick enough nor grippy enough to go underfoot. If you want one tile across walls and floor confirm the manufacturer rates it for both.

Do Not Forget Adhesive and Grout

The tiles are only part of order. Powdered cementitious adhesive covers roughly 4 to 5 square metres per 20kg bag on walls with a 6mm notched trowel, less for large format floor tiles which need a bigger notch and back buttering. Use flexible adhesive over underfloor heating or timber floors, and never ready mixed tub adhesive on a floor.

Grout runs at roughly 0.5kg per square metre for 300 x 300mm tiles with 3mm joints and less for larger tiles with fewer joints. Buy slightly over because matching a second batch of grout colour mid job is harder than it sounds. Our Grout and Adhesive Calculator UK works out both in detail.

Worked Example

A 2.4m x 2m bathroom tiled to full height at 2.4m on all four walls with 600 x 300mm tiles:

• Wall area: (2.4 + 2 + 2.4 + 2) x 2.4 = 21.1 m²
• Minus the door at 1.6 m² and window at 0.8 m²: 18.7 m²
• Tiles at 6 per m²: 113 tiles
• Plus 15 percent bathroom wastage: 130 tiles
• At 8 tiles per box: 17 boxes

The same room in herringbone would push the order to around 134 tiles before boxing, which shows how much pattern choice costs.