Counting floor tiles is a matter of dividing the area to be tiled by the area of one tile, then adding an allowance for cutting and breakage. The area to be tiled is the floor itself plus the skirting strip that runs around the walls.
Floor area = L × B
L and B are the room length and breadth in metres.
Skirting area = (2L + 2B − 0.9) × h
h = skirting height in metres. 0.9 m is deducted for a standard door opening, which has no skirting.
Tiles required = (Floor area + Skirting area) / (tile length × tile breadth) × 1.05
The 1.05 adds 5% for cuts and wastage. Round up to a whole tile.
Worked example
A room 4 m long and 3 m wide, with 100 mm skirting, tiled with 600 × 600 mm tiles:
- Floor area: 4 × 3 = 12 m²
- Skirting area: (8 + 6 − 0.9) × 0.1 = 1.31 m²
- Total area: 13.31 m²
- Area of one tile: 0.6 × 0.6 = 0.36 m²
- Tiles: 13.31 / 0.36 = 36.97, plus 5% = 38.8 → order 39 tiles
Tiles are sold by the box, so check the box quantity and round up to whole boxes. Keep a few spares from the same batch for future repairs — colour varies between batches.
Calculate it online
The free tiles & flooring calculator does this for any room and tile size, with the wastage allowance as an input.