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Project guide

How many floor tiles do I need for a bathroom?

Bathroom floors are small but full of cuts: round the toilet, the basin pedestal and the bath panel. Measure the floor, add the waste allowance and buy whole boxes from one batch.

Updated Based on manufacturer guidance, sources below

The short answer

Tiles (m²) = length x width, plus 10% for a straight layout or 15% for diagonal, rounded up to whole boxes. A 2.4 x 1.8m bathroom is 4.3 m², so buy about 5 m² of tiles, one 20kg bag of adhesive and one 5kg bag of grout.

The formula

  • Floor area (m²) = length x width (do not take off the toilet or basin: you still cut round them)
  • Tiles to buy (m²) = area x 1.1 for straight, x 1.15 for diagonal
  • Adhesive and grout follow the floor tiling calculator

Worked example

A 2.4 x 1.8m bathroom floor in 300 x 300mm tiles, laid straight:

  • Area: 2.4 x 1.8 = 4.32 m²
  • Plus 10%: 4.75 m², so buy 5 m² (about 56 tiles)
  • Adhesive: 1 x 20kg bag
  • Grout: 1 x 5kg bag

Work it out for your job

Change the measurements and the quantities update straight away.

Floor area
4.3 m²
Tiles
53 at 300 x 300mm
Adhesive
18.3 kg
Grout
1.5 kg

Your list

  • 5m² of tiles including 10% (buy whole boxes)
  • 1Flexible tile adhesive, 20kg bags
  • 1Tile grout, 5kg bags
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Materials checklist

  • Floor tilesChoose a slip-resistant floor tile. Bought by the box: round up to whole boxes.
  • Flexible tile adhesiveA flexible cement-based adhesive, 20kg bags, suitable for floors and any underfloor heating.
  • GroutCement-based floor grout, 5kg bags.
  • Sanitary siliconeRound the bath, the toilet pan and where the floor meets the walls.

You'll also need

  • Tile backer board or an uncoupling mat on timber floors
  • Primer for the floor
  • Tanking where the floor will get wet, for example a walk-in shower
  • Spacers or a levelling clip system, notched trowel, tile cutter and knee pads

Step by step

  1. Remove the toilet and pedestal if you canTiling under them gives a neater finish and fewer awkward cuts.
  2. Prepare the floorIt must be flat, clean and rigid. Overboard a timber floor that flexes.
  3. Set out from the doorwayPlan the layout so full tiles are at the door and cuts end up under the bath panel or behind the toilet.
  4. Fix and groutSpread adhesive with a notched trowel, bed each tile fully, and grout once the adhesive has set.
  5. Seal the edgesUse silicone, not grout, where the floor meets the bath, the pan and the walls.

Tips from the manufacturers

  • Do not take the toilet or basin off the floor area: the cuts round them use whole tiles.
  • Small bathrooms often look better in larger tiles, but large tiles need a flatter floor.
  • Buy all the tiles from the same batch and keep a few spares for repairs.

Mistakes to avoid

  • Tiling straight onto floorboards that flex, which cracks tiles and grout.
  • Ordering the exact area with no allowance for the cuts round the toilet and pipes.
  • Grouting the joint along the bath instead of using silicone.

Frequently asked questions

How many floor tiles do I need for a small bathroom?

Multiply the length by the width and add 10%. A 2 x 1.5m bathroom is 3 m², so buy 3.3 m², which rounds up to the next whole box.

Should I tile under the bath?

No. Tile up to the bath panel. Tile under the toilet and pedestal if you can take them out, as the finish is neater.

How much extra tile should I buy?

About 10% for a straight layout and 15% for diagonal, plus a few spares from the same batch for future repairs.

What size tile is best for a small bathroom?

There is no single answer. Larger tiles mean fewer grout lines but need a flatter floor and give more waste in a very small room.

Sources

Quantities are estimates for typical jobs, using the coverage figures above. Products vary, so check the data sheet for the product you buy, and talk to a professional for structural, electrical or gas work. SmartBuild is independent and not affiliated with any of the manufacturers listed.

Tiling a floor: how many tiles, and how much adhesive and grout?Measure the floor, add an allowance for cuts, then work out adhesive and grout from the tile size. How many tiles do I need, and how much adhesive and grout?To work out how many tiles you need, find the area, divide by the size of one tile and add 10% for cuts. Adhesive and grout depend on where you are tiling and the joint size. Tiling a wall or splashback: tiles, adhesive and groutMeasure the wall, take off anything you are not tiling, add an allowance for cuts and work out adhesive and grout from the tile size.

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