Buy 10% extra tile for a straight or offset layout, 15% for a diagonal layout and 20% for herringbone. Add a few more percent for small rooms, rooms with many corners, and large-format tile, where one bad cut costs a big piece.
| Layout | Typical waste | Where the waste comes from |
|---|---|---|
| Straight (grid) | 10% | Cuts only at walls and obstacles |
| Offset (brick, 1/2 or 1/3) | 10% | Offcuts from one row often start the next |
| Diagonal (45°) | 15% | Every tile along every wall is cut at an angle |
| Herringbone | 20% | Angled cuts at every edge, many small leftover pieces |
What the waste factor does to a real order
A 10 × 12 ft floor (120 sq ft) in 12 × 24 in porcelain with 1/8 in joints, sold in boxes of 15.5 sq ft. With no waste at all it takes 60 tiles. By layout:
| Layout | Waste | Tiles to buy | Boxes |
|---|---|---|---|
| Straight (grid) | 10% | 65 | 9 |
| Offset / brick | 10% | 65 | 9 |
| Diagonal (45°) | 15% | 68 | 9 |
| Herringbone | 20% | 71 | 10 |
Going from straight to herringbone on this floor costs about 1 extra boxes. That difference is worth knowing before you fall in love with a pattern at the showroom. The tile calculator sets the waste automatically when you pick a layout.
Why small rooms waste more
Waste comes from the edges, and small rooms are mostly edge. We counted, for a straight grid with 1/8 in joints, how many tile positions need a cut because they meet a wall:
| Room | 12 × 12 in tile: cut tiles | 24 × 24 in tile: cut tiles |
|---|---|---|
| Bathroom floor, 5 × 8 ft | 12 of 40 (30%) | 6 of 12 (50%) |
| Kitchen, 10 × 12 ft | 21 of 120 (18%) | 10 of 30 (33%) |
| Open-plan area, 15 × 20 ft | 34 of 300 (11%) | 17 of 80 (21%) |
In a small bathroom, most tiles touch a wall, so most of them get cut. Many cut-offs are too small to reuse. That’s why a 10% allowance that works in an open kitchen can leave you short in a powder room, especially with large tiles. For rooms under about 50 sq ft, use 15% even for a straight layout.
Why diagonal and herringbone waste more
In a straight layout, the piece you cut off at one wall can often finish the row on the opposite wall. On a diagonal, every tile along every wall is cut into a triangle, and the two halves only fit back together if your cuts are perfect and the room is square. Herringbone is worse: each edge piece is an odd shape, and planks have to be cut on both ends near walls.
Other things that push waste up
- Large-format tile. A tile 24 in or longer leaves big offcuts that may not fit anywhere else, and a single cracked tile is a bigger share of the order.
- Natural stone and handmade tile. Some pieces will be chipped or off-color, and you’ll want to sort them.
- Obstacles. Toilet flanges, floor vents, island bases and door jambs all add cuts.
- Patterns that must line up, like a border or a matched vein.
How many spares to keep
After the job, keep at least a few whole tiles, or a full box if you can. Tile lines get discontinued, and replacing one cracked tile years later is easy only if you have a match from the same lot. Count those spares inside your waste allowance, not on top of it.