The basic math
Tile quantity starts with two areas: room area ÷ tile area = tiles needed. Measure the room's length and width, multiply for total square footage, then divide by the area of a single tile (also length × width, in the same units).
That raw number is never what you actually buy, though — real installs always need a buffer for cuts, breakage, and pattern layout.
Why you always buy extra
- Straight-lay pattern: add 10% for cuts along walls and edges.
- Diagonal pattern: add 15–20% — diagonal cuts waste more material per tile.
- Complex rooms with alcoves, islands, or lots of corners: add 15% regardless of pattern.
- Future repairs: keep a few extra tiles from the same batch — dye lots vary, and matching tile years later is often impossible.
| Layout | Waste allowance |
|---|---|
| Straight lay, simple room | 10% |
| Diagonal lay | 15–20% |
| Complex room shape | 15%+ |
How to estimate with DailyToolsAI
Enter room dimensions
Length and width of the area you're tiling.
Enter tile size
The Tile Calculator supports common sizes or custom dimensions.
Apply a waste percentage
Pick your layout style and the tool adds the right buffer automatically.
Tiles are usually sold by the box, not individually — round your final number up to the nearest full box, since most suppliers won't split one.
Don't forget grout lines
Tile size on the box is the tile itself, not the tile plus grout gap. For most rooms this rounding error is negligible, but for very large-format tile or very wide grout lines, factor the actual spacing into your area math for a more precise count.
Calculate tiles for your room
Free, instant, works for any tile size and layout.