Tile Calculator
Calculate how many tiles and square feet you need, including waste.
10% waste suits straight layouts; use 15% for diagonal or herringbone patterns and rooms with many cuts.
Few things derail a tiling project like running out of tile with three feet of floor left — especially when the store no longer stocks your exact dye lot. Our tile calculator above tells you how many tiles and how much total square footage to order, with the right waste factor built in for your layout.
How Tile Quantity Is Calculated
The calculation runs in three steps:
Floor area = Length × Width (in feet)
Tile area = (Tile width × Tile length) ÷ 144 (tile dimensions in inches, converted to square feet)
Tiles needed = (Floor area ÷ Tile area) × (1 + Waste factor), rounded up
So a 10 × 8 ft bathroom floor (80 sq ft) tiled with 12 × 12 inch tiles (1 sq ft each) needs 80 tiles before waste — and 88 tiles with the standard 10% allowance.
Why You Must Order Extra Tile
Ordering the exact mathematical number of tiles is the most common DIY tiling mistake. You need extra for four unavoidable reasons:
Cuts. Every edge row against a wall, every corner, and every pipe or vent penetration consumes partial tiles. The offcut from one side often can’t be reused on the other.
Breakage. Tiles crack in transport, during cutting (especially brittle porcelain), and occasionally under the trowel. Even pros break a few.
Dye lot matching. Tile color and shade vary subtly between production batches. If you have to reorder later, your new tiles may visibly mismatch — the number one reason to overbuy up front.
Future repairs. A box of spares in the garage means a cracked tile five years from now is a 20-minute fix instead of a whole-floor problem.
Choosing the Right Waste Factor
- 10% — straight (grid) layout in a simple rectangular room. This is the default.
- 15% — diagonal, herringbone, or offset patterns, rooms with lots of corners, angles, or built-ins. Diagonal layouts cut every perimeter tile at 45°, which wastes more material.
- 20% — large-format tiles in small rooms. When a single tile covers a big share of the floor, each cut wastes proportionally more.
Common Tile Sizes at a Glance
| Tile size | Tiles per 10 sq ft (before waste) |
|---|---|
| 4 × 4 in | 90 |
| 6 × 6 in | 40 |
| 12 × 12 in | 10 |
| 12 × 24 in | 5 |
| 18 × 18 in | 4.5 |
| 24 × 24 in | 2.5 |
Tips Before You Buy
Buy by the box, think in square feet. Tile is sold in boxes covering a set area (often 10–15 sq ft). Divide your total needed area by the box coverage and round up to full boxes.
Check the box labels for shade/caliber codes and make sure every box matches — even within one order, mixed lots happen.
Dry-lay a row first. Laying one row of loose tiles across the room reveals whether you’ll end with an awkward sliver cut at the wall; shifting your starting line can eliminate it and reduce waste.
Don’t forget trim pieces: bullnose edges, transition strips, and matching grout (try our grout calculator) are separate line items.
Frequently Asked Questions
How many 12×12 tiles do I need for 100 square feet? 100 tiles before waste; order 110 for a straight layout or 115 for a diagonal one.
Do wall tiles calculate the same way? Yes — multiply wall width by height for each wall, subtract large openings, and add the same waste factors. Backsplashes with outlets and window sills lean toward 15%.
Can I return unused boxes? Most big-box stores accept returns of full, unopened boxes — one more reason rounding up is low-risk. Check the policy where you buy.
Estimates are for planning purposes. Confirm coverage per box with your specific product.