How to calculate how many tiles you need
Tiles are sold and priced by the square metre, so the easiest way to plan a tiling job is to work in square metres rather than counting tiles. This tile calculator takes the area, adds wastage for cuts and your layout pattern, then prices tiles, adhesive, grout and the tiler’s time — for a wall or a floor.
Step 1: the tiled area
Measure each wall or floor section and multiply width by height. Subtract windows, doors and anything the tiles will not cover, like a bath panel. A bathroom tiled to full height around a bath and shower often comes to 10–15 m².
Step 2: add wastage
Allow 10% for a straight layout. The pattern adds more: 2 points for brick bond, 5 for diagonal and 8 for herringbone, because of the extra cuts. 12 m² laid straight means ordering 13.2 m².
Step 3: turn m² into tiles
Divide the order area by the area of one tile. A 30 × 60cm tile covers 0.18 m², so you need about 5.6 per m². A 25 × 40cm tile is 10 per m², and a 60 × 60cm tile under 3 per m². Boxes usually state the m² they cover.
Worked example: 12 m² of bathroom wall
Mid-range tiles, standard size, straight layout.
| Item | How it is worked out | Cost |
|---|---|---|
| Tiles | 13.2 m² (12 m² + 10%) × £34 | £448.80 |
| Adhesive | 12 m² × £5.50 | £66.00 |
| Grout | 12 m² × £2.50 | £30.00 |
| Labour | 12 m² ÷ 10 m² a day = 1.2 days × £220 | £264.00 |
| Total | £808.80 |
The same wall in budget tiles is about £598; in premium tiles about £1,218. Removing old tiles and preparing the wall are extra.
What changes the cost
Wall vs floor
Floor tiles are thicker and heavier, so they take about 40% more adhesive, and a tiler lays them more slowly because the floor has to be level. The same area of floor usually costs more in labour than wall.
Tile size
Grout depends on the length of the joints. Mosaic uses about 2.4 times as much grout as standard tiles, and large-format tiles only 0.6 times. Large tiles are heavy and must be perfectly flat, and mosaic is fiddly, so both slow the job down.
Pattern
Herringbone adds 8 points of wastage and cuts a tiler’s daily output to about 60% of a straight layout. Same tiles, same room — but noticeably more expensive to lay. Diagonal sits in between.
Before you start
Surface preparation
Tiles need a sound, flat, dry surface. Old tiles, loose plaster or a wooden floor that flexes may need removal, backer board or levelling first. In showers, the wall should be tanked (waterproofed) before tiling. Switch on removal and preparation in the calculator if they apply.
Order everything at once
Buy all the tiles from one batch — colour can vary between batches. Keep a few spare to replace cracked tiles later, since the exact range may be discontinued.
Worked example: 6 m² of herringbone floor
The same mid-range tiles on a floor, in herringbone: more wastage, more adhesive and slower laying.
| Item | How it is worked out | Cost |
|---|---|---|
| Tiles | 7.08 m² (6 m² + 10% + 8 points) × £34 | £240.72 |
| Adhesive | 6 m² × £5.50 × 1.4 for floor tiles | £46.20 |
| Grout | 6 m² × £2.50 | £15.00 |
| Labour | 6 m² ÷ 5.1 m² a day ≈ 1.18 days × £220 | £258.82 |
| Total | £560.74 |
Floor speed (×0.85) and herringbone speed (×0.6) cut the tiler’s 10 m² a day to 5.1 m². Half the area of the wall example costs nearly 70% as much.
Adhesive, grout and tools
Choosing adhesive
Ready-mixed tub adhesive suits small wall tiles in dry areas. Floors, large-format tiles, wet areas and underfloor heating need a powdered cement-based adhesive, usually flexible. Check the bag’s coverage — it depends on the notch size of the trowel.
Choosing grout
Narrow joints on wall tiles take standard grout; wide joints and floors need a grout rated for their width. In showers, a water-resistant or epoxy grout lasts longer. Use silicone, not grout, where tiles meet the bath or a different surface.
Related planning
Our guide to how many tiles you need covers wastage by layout and adhesive in more detail. For the rest of a bathroom or kitchen floor, compare tiles with LVT in the flooring calculator, and use the paint calculator for walls that are not tiled.
A full bathroom renovation also includes plumbing, sanitaryware and electrics, which need a quote from a fitter.