Setting out
Balanced cuts from the centre line (equal cuts both ends)
- where
- end space at each wall (mm)
- run length, wall to wall (mm)
- whole tiles across (largest number giving a cut at least the smallest acceptable size)
- tile size along the run (mm)
- joint width (mm)
- cut tile at each end (mm)
- edge gap at each wall (mm)
Explain this equation
Sets out a row of tiles from the centre of a wall or floor so the cut tiles at each end are the same size, and avoids thin cuts.
L is the run from wall to wall, t the tile size along the run and j the joint. n is the number of whole tiles. S is the space left at each end, and c the cut tile size after taking off the edge gap e and half a joint.
The whole tiles with one joint each take up n × (t + j); half of what is left goes to each end. A row of whole tiles has one more joint than tiles, so each end loses half a joint, and any movement gap at the wall. n is the largest number that still leaves cuts of at least the size you accept; if not, one tile is dropped and the cuts grow by half a tile.
Sense check: a 3.4 m run of 600 mm tiles with 3 mm joints gives five tiles with 191 mm cuts, which is under half a tile, so use four tiles with 492.5 mm cuts.
Watch out: check both ends of the room; walls are rarely parallel.
Sets out a run from its centre so the cut tiles at both ends are equal, and drops one whole tile if the cuts would otherwise be smaller than you accept.
Enter your values to see the result.
Good to know
The whole tiles and their joints take up n × (t + j); what is left is split equally between the two ends. Each end then loses half a joint (the run has one more joint than whole tiles) and any edge gap. Odd n puts a tile on the centre line, even n puts a joint there. TTA and Topps guidance is to centre walls and avoid thin cuts: under about half a tile, shift by half a tile.
Common mistake
Starting with a whole tile in one corner and ending with a sliver in the other, which is the first thing a customer notices.
Limits
One direction at a time; run it for both directions of a floor. Walls out of square or out of parallel give different cuts at each end of the wall, so check both ends.
Sources
Results are calculations from the published methods and manufacturer figures shown, and depend on the data you enter. Always follow the tile, adhesive and grout manufacturers’ instructions, BS 5385 and the Tile Association guidance. Coverage rates vary by product and substrate. Check prices and VAT rules with your own records and HMRC.