How this calculator works
- Step 1Arealength × widthThe floor or wall to cover.
- Step 2Per tile(tile + joint)²Each tile covers its own size plus the grout gap.
- Step 3Buy+ waste, round upAdd extra for cuts, then round up to whole boxes.
Divide the area by what one tile covers, add a waste allowance, and round up. The calculator also lays the tiles out in a grid, counting every cut piece as a whole tile.
Worked example: a 12 × 10 ft bedroom
- Tiles
area × (1 + waste) ÷ ((L + j) × (W + j))
- L, WTile size 600 × 600 mm
- jJoint 2 mm
- Area12 ft × 10 ft11.15 m²
- One tile covers0.602 m × 0.602 m0.3624 m²
- Tiles, exactarea ÷ cover30.76
- With 10% extraround up34 tiles
- Boxes of 434 ÷ 4, round up9 boxes
Without any extra you would need 31 tiles, which leaves nothing for cuts or a cracked tile.
Tile size changes the count
Bigger tiles mean fewer pieces, but each cut wastes more, so keep a larger allowance for slabs.
Read the result
The grid count of 42 treats every edge piece as a whole tile; the real need usually sits between the area count and the grid count.
Offcuts from one edge can often fill the opposite edge, which is why the area count with a waste allowance is the headline.
Assumptions and limits
- RectangleSplit L-shaped rooms and add the parts.
- Straight layDiagonal and herringbone patterns need more extra.
- Not includedSkirting, steps, adhesive and grout quantity.
- Rule of thumbThe waste figure is your choice, not a standard.
Other building estimates
Tiles cover an area. Walls, paint and concrete have their own quantities.
For the area of irregular floors, start with the area calculator. The paint calculator covers walls, and the concrete calculator a slab underneath.
Common mistakes
Mistake: Buying exactly the area divided by tile size.
Instead: Add extra for cuts and breakage.
Mistake: Treating a 2 × 2 ft tile as exactly 610 mm.
Instead: Use the millimetre size on the box, usually 600 mm.
Mistake: Buying top-up boxes months later.
Instead: Buy enough from one batch so the shade matches.
Checking the method
A separate script re-works every golden value in exact integer micrometres, searching upwards for each count instead of dividing.
Read how we test our calculators, or browse more everyday tools.