How much tile waste should you buy?

Buy too little tile and the next batch won't match. Buy too much and you've wasted money. Here's how much extra — the "waste allowance" — you actually need, and why it changes with your layout.

The short answer

For a standard straight (grid) layout, add 10% to your measured area. For diagonal or herringbone patterns, or a room chopped up by lots of corners and fixtures, add 15%. Very intricate layouts can justify 20%.

Why waste happens

Every time a tile meets a wall, a doorway, a cabinet or a drain, you cut it — and the offcut usually can't be reused anywhere else. A few tiles also crack during handling and setting. That's the "waste," and it's completely normal. The overage covers it so you don't stop mid-job for another store run.

A quick example

Say you're tiling a 120 square foot floor with 12×12 inch tiles (one tile = one square foot):

• Straight layout, 10%: 120 × 1.10 = 132 tiles
• Diagonal layout, 15%: 120 × 1.15 = 138 tiles

Then round up to whole boxes, since stores sell tile by the box, not the piece.

The batch trap most people miss

Tile is produced in batches (called "dye lots" or "shade variations"), and color can shift slightly between them. If you run short and buy more later, the new box may not match. So buy your whole job plus the waste from a single batch now, and keep a few spare tiles for future repairs — a cracked tile two years from now is far cheaper to fix if you have a match in the garage.

Layout changes everything

A simple grid on a square room wastes very little. A diagonal lay means every edge tile is a triangle cut, and herringbone multiplies cuts even further. Large-format tiles in a small, irregular bathroom also waste more, because each cut removes a big piece. When in doubt, go up a notch.

Waste by layout

The 10% and 15% figures are averages. The pattern you choose moves the number more than anything else, so here is a fuller breakdown to set the waste box in the calculator.

Walls and showers are counted differently

For a wall, measure each wall's width times the height you are tiling, then subtract windows and the tub or shower opening. A standard 5-foot tub surround tiled to 6 feet above the tub has a back wall of 5 × 6 = 30 ft² and two end walls of about 2.5 × 6 = 15 ft² each, so 60 ft² before waste.

Then add the pieces that are not field tile. Exposed edges need bullnose tile or a metal edge trim, measured in linear feet. A shower niche adds its back, sides, top and bottom: a 12 × 24 inch niche that is 4 inches deep adds about 2 ft² of back plus another 2 ft² for the sides, top and bottom. Accent strips are ordered separately, by the piece.

Round to boxes, not to tiles

The tile count is not the shopping list; the box count is. Say your floor needs 132 ft² with waste and the tile you like comes in boxes of 15.5 ft². That is 8.5 boxes, so you buy 9, which gives you 139.5 ft²: about 7 ft² of extra spares for free. Before you round up to a tenth box, check whether the extra half box is really needed, and before you round down, remember the batch trap below.

What to do with the leftovers

Most stores accept unopened boxes back within a return window, so a full spare box is not wasted money if the job goes well. Opened boxes are usually not returnable. Keep 5 to 10 loose tiles, or one box for a large floor, labeled with the room and the lot number. If a tile cracks years later, a matching spare saves you from regrouting a whole section around a tile that does not match.

Quick answers

Is 10% enough for tile? Yes for a straight layout in a simple room. Use 15% for diagonal, herringbone or cut-heavy spaces.

Should I buy extra for repairs? Yes — keep a few tiles from the same batch.

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