For a straight grid in a simple rectangular room, order about 10% more tile than the floor area. Diagonal, herringbone and other intricate layouts usually need about 15%, and L-shaped or curved rooms 15 to 20%. The pattern matters because every tile that meets a wall at an angle has to be cut, and angled offcuts are rarely reusable.
The tile calculator counts tiles and boxes with your tile size, grout joint and waste allowance, and raises the default allowance when you choose a diagonal layout.
Common tile layout patterns
| Pattern | What it looks like | Typical extra |
|---|---|---|
| Straight (grid) | Joints line up in both directions | About 10% |
| Running bond (brick, offset) | Rows shifted by part of a tile, like brickwork | About 10%; more with long tiles |
| Diagonal | A grid turned 45° to the walls | About 15% |
| Herringbone | Rectangles set in a zigzag | About 15%, more in small rooms |
| Basketweave, mosaic, mixed sizes | Repeating groups of tiles | About 15% |
| Any pattern in an L-shaped or curved room | Extra corners and edges | 15 to 20% |
Straight vs diagonal vs herringbone
In a straight layout, the cut pieces at one wall can often be used at the opposite wall, so little is thrown away. Turn the same grid 45 degrees and every edge tile becomes a triangle. The two halves of a diagonally cut tile can sometimes be used on opposite sides of the room, but corners, doorways and out-of-square walls break that pairing.
Herringbone uses rectangular tiles meeting at right angles. Every row ends at the wall in an angled cut, and a herringbone floor also has to start from a carefully centered line, which adds cuts at both sides of the room.
How tile size and room shape affect waste
- Large tiles cover the floor with fewer pieces, but each cut can waste a large piece, and there is less room for error.
- Small tiles and mosaics take more pieces and more time, but they are forgiving around obstacles and the offcuts are small.
- Room shape often matters more than pattern. A small bathroom with a toilet, vanity and tub apron can waste more than a large open kitchen.
- Walls are rarely square. Tapered cuts along an out-of-square wall use up tiles that a perfect room would not.
Estimating tile quantity for each pattern
- Measure the floor area. Split L-shaped rooms into rectangles and add them.
- Divide by the area of one tile to get the base count. A 12 × 12 in tile covers 1 sq ft; a 12 × 24 in tile covers 2 sq ft.
- Multiply by 1 plus the allowance for your layout, for example 1.15 for diagonal.
- Round up, then convert to boxes using the pieces or square feet per box on the carton.
Worked example: an 8 × 10 ft bathroom floor
The floor is 80 sq ft. Ignoring the grout joint, which slightly reduces the count, the number of tiles to buy is:
| Tile size | Base count | Straight (10%) | Diagonal or herringbone (15%) | Complex room (20%) |
|---|---|---|---|---|
| 12 × 12 in | 80 | 88 | 92 | 96 |
| 12 × 24 in | 40 | 44 | 46 | 48 |
| 6 × 6 in | 320 | 352 | 368 | 384 |
| 3 × 12 in subway | 320 | 352 | 368 | 384 |
Notice that the allowance adds the same share whatever the tile size, but in real rooms large-format tile often ends up at the higher end, because one bad cut costs a whole large tile.
Tips for reducing cuts and breakage
- Dry-lay a row in each direction before you set anything, so cuts at both walls are similar in size and neither is a thin sliver.
- Start diagonal and herringbone layouts from a centered reference line, not from a wall.
- Open all boxes and blend tiles from several boxes as you go, so slight shade differences spread out.
- Buy all the tile, including extras, in one order so it comes from the same production run.
- Keep a few spare tiles. Styles get discontinued, and a matching replacement can be impossible to find later.
Laying plank flooring instead? See how much extra flooring to buy.
Sources
- Clé Tile: How Much Extra Tile to Buy (overage by layout and room shape, tile size, spares)
- Wayfair: How to Measure Flooring for Installation (waste allowances for hardwood, laminate, diagonal layouts and tile)
