Calculators › Tiler
Free tiler calculator
Tile calculator: tiles, adhesive and grout for a floor or wall
Enter the area, the tile and where it is going to see how many tiles to order and how many bags of adhesive and grout to fix them. Adhesive coverage follows the BAL and Weber datasheets for the bed you will use, and grout follows the Mapei formula from the tile size, thickness and joint width, so a 300 × 300 floor takes a third of the grout most guides tell you to buy.
What you need
Tiles
- Area
- 12.0 m²
- Tiles
- 144 × 300 × 300mm10.9 per m² with a 3mm joint, plus 10% for the straight layoutWickes/Topps 10%; diagonal and herringbone from trade practice
Adhesive and grout
- Tile adhesive (powdered, 20kg)
- 3 bags5.2m² a bag on a floor, 10mm notch solid bed, plus 10%. Use a flexible S1 adhesive; ready-mixed tubs are for dry walls onlyBAL SPF: 0.26m²/kg on floors
- Grout
- 1 × 5kg bags4.2kg: 0.32kg per m² for a 300 × 300 × 10mm tile with a 3mm joint, plus 10%Mapei Ultracolor Plus: (L + W) ÷ (L × W) × thickness × joint × 1.6
- Spacers
- 2 × pack of 2502 per tile at 3mm
Sundries
- Tile trim
- 0 × 2.5m lengthsnone: floors and walls tiled to the ceiling and into corners need no trim
- Primer
- 2 litreson plaster, plasterboard, anhydrite screed and anything dusty, at about 1 litre per 10m² diluted
Round up to whole packs and bags. Figures include the wastage you chose and match TradeCalc in the app.
For tilers: turn this into a quote
In the app, TradeCalc hands these quantities straight to ProQuote with your regional material prices, and the customer gets a branded PDF. Free to download.
Or claim your free profile link nowHow the maths works
- Tiles per square metre use the tile plus its joint: a 300 × 300 tile with a 3mm joint covers 303 × 303mm, so 10.9 per m² rather than 11.1. Wastage is 10% for a straight grid or brick bond, 15% for diagonal and 20% for herringbone, because every edge tile is cut.
- Adhesive depends on where it goes, from the BAL SPF and Weber Rapid SPF datasheets: a 20kg bag does about 10m² on a dry wall with a 6mm notch, 8m² on a solid bed in a shower, 5.2m² on a floor with a 10mm notch, and about 3m² on a 6mm solid bed under large format or on an uneven floor. 10% is added.
- Grout uses the Mapei formula: (length + width) ÷ (length × width) × tile thickness × joint width × 1.6 gives kg per m². A 300 × 300 × 10mm tile with a 3mm joint is 0.32kg/m², so a 5kg bag does about 14m²; a 200 × 100 metro tile at 8mm with a 2mm joint is 0.38kg/m². 10% is added.
- Spacers are two per tile, one for each shared edge, in packs of 250. Trim is only for exposed edges in 2.5m lengths; a floor needs none.
- A shower gets a tanking kit before tiling at about 5m² of wall a kit. An uneven floor gets self-levelling compound at about 4.5m² a bag at 3mm. Primer is about a litre per 10m² on plaster, plasterboard, anhydrite and dusty backgrounds.
- If you enter the m² per box the tile count is rounded up to whole boxes. Keep a few spares from the same batch: a later batch can be a different shade or size.
Worked example
A 4m by 3m floor is 12m². With 300 × 300mm tiles at a 3mm joint laid straight that is 10.9 tiles per m², so 144 tiles with 10% wastage, 3 bags of 20kg adhesive on a 10mm notch solid bed, 1 bag of 5kg grout (4.2kg by the Mapei formula) and 2 packs of 250 spacers.
Questions people ask
How many tiles do I need per square metre?
Divide 1 by the tile-plus-joint area in metres. A 300 × 300mm tile with a 3mm joint is 0.0918m², so about 10.9 per m². A 600 × 600mm tile is about 2.7 per m². Then add wastage and round up to whole boxes.
How much wastage should I allow for tiling?
10% for a straight grid or brick bond in a simple room, which is what Wickes and Topps add. 15% for a diagonal layout or large-format brick bond, and 20% for herringbone, because every edge tile is a cut and the offcuts rarely reuse. A fiddly bathroom with lots of pipes can push a straight layout to 15%.
How much tile adhesive do I need?
A 20kg bag of powdered adhesive does about 10m² on a dry wall with a 6mm notch, 8m² in a shower on a solid bed, about 5m² on a floor with a 10mm notch, and only 2 to 3m² on a solid 6mm bed under large format, from the BAL SPF and Weber Rapid SPF datasheets. Ready-mixed tubs are for dry walls only.
How much grout do I need?
Mapei's formula is (length + width) ÷ (length × width) × thickness × joint × 1.6 in millimetres, which gives kg per m². For 300 × 300 × 10mm tiles with a 3mm joint that is 0.32kg/m², so a 5kg bag does about 15m², not 5m². Small tiles and wide joints use far more: 100 × 100 mosaics at 3mm need over 1kg/m².
Do I need to prime before tiling?
On plaster, plasterboard, anhydrite screed and any dusty or porous surface, yes. Primer stops the background drawing water out of the adhesive too fast. Anhydrite must be primed and the laitance sanded off first. On a sound concrete floor it is often optional, but it does no harm.
Does a shower need tanking?
Yes. Tiles and grout are not waterproof, so a shower enclosure gets a tanking membrane or a kit of liquid membrane, tape and corners before tiling, then a flexible adhesive and grout on top. A kit covers about 5m² of wall; check the one you buy.
Related calculators
Tiles by size and joint, adhesive split wall and floor, grout by the formula, tanking kits for the wet zone to BS 5385, backer boards on the wet walls and a tile-weight check against the substrate.
Paint calculator: how much paint you need for a roomHow many litres and tins of emulsion, ceiling paint, woodwork paint or masonry paint a room needs by grade, coats and coverage, with the mist coat, undercoat and prep.
Plaster calculator: bags of MultiFinish, HardWall, bonding, one-coat and renderHow many 25kg bags of plaster or render a room or wall needs, from British Gypsum coverage rates, plus primer, beads, scrim, dot-and-dab adhesive and water.
Want a price, not just quantities? Read what this job costs, then post it and let trades quote from your photos.
