The rule of thumb
Add at least 10 percent to the measured area for a simple straight layout. Add more when the pattern or the room produces more cuts.
| Layout | Overage | Why |
|---|---|---|
| Straight grid | 10% | Cuts only at the edges |
| Offset / brick bond | 10 to 15% | Offcuts at every row end |
| Diagonal | 15% | Every edge tile is cut at an angle |
| Herringbone, chevron | 15 to 20% | Many small angled cuts |
Where the waste comes from
- Edge cuts. Walls are rarely a whole number of tiles wide, so the last tile in each row is cut and the offcut is often too small to use.
- Obstacles. Toilets, pipes, floor vents and door frames all need notched or curved cuts.
- Breakage. Some tiles arrive chipped, and some crack while cutting, especially natural stone and large porcelain.
- Shade sorting. Tiles vary slightly, and installers sometimes set aside pieces that do not blend.
When to add even more
Small rooms waste a larger share than big ones, because nearly every tile touches a wall. Large-format tiles waste more for the same reason: each cut discards a bigger piece. Bathrooms with many fixtures, rooms with lots of corners and irregular shapes all justify going toward the top of the range.
Keep a spare box
After the job, store at least one full box. If a tile cracks years later, you can replace it with an exact match. Tile ranges are discontinued often, and a new batch of the same product may differ slightly in shade or size.
Check the batch before you start
Boxes carry a batch, lot or shade code. Make sure all your boxes share the same code, and buy the overage at the same time as the main order so it comes from the same batch.
Run the numbers
The tile calculator applies the overage for the pattern you pick and rounds up to whole boxes.
Frequently asked questions
Is 10% extra tile enough?
For a straight layout in a medium or large room, 10 percent is usually enough. Diagonal and herringbone layouts need more.
Can I return unused tile?
Many stores accept unopened boxes, but policies vary and special orders are often final. Ask before you buy.
Does mosaic tile need overage?
Yes, though mosaic sheets cut easily, so 10 percent is usually enough unless the room has many fixtures.
Do the math for your own project.
Open the tile calculator