How Much Extra
Tile Should I Buy?
Buying extra tile is necessary to cover corner cuts, transit breakage, installation errors, and to save spare tiles for future repairs. The classic 10% rule is a base starting point, but complex patterns like herringbone require 15–20% overage. Ordering too little risks running out and having to buy a different dye lot (color mismatch). Use the tile waste calculator to find your precise quantities.
Calculate Exact Tile Overage
Our calculator accounts for tile sizes, patterns, and full-box rounding to show exactly how many boxes to buy.
Where Does the Extra Tile Go?
Tile overage is not just wasted material. It is distributed across four distinct project components:
1. Cutting & Perimeter Waste
5–12% shareLeftover scrap pieces from wall edges, corner miters, and trim lines that cannot be reused elsewhere.
2. Transit & Jobsite Breakage
2–3% shareTiles that arrive cracked in the box or break while being handled, cut, or back-buttered.
3. Installer Error Margin
2–5% shareMiscalculated cuts, drilling mistakes for pipe penetrations, or cracking under heavy snap cutting.
4. Attic Stock (Repair Spares)
2–3% shareA stash of 10–15 matching tiles saved for future repairs (plumbing leaks, cracks, dye-lot matching).
Why Attic Stock is Crucial
Attic stock is the spare tile you save in your garage or attic after a tiling project is finished.
Dye-Lot Matching:
Tile is manufactured in batches called dye-lots. If a tile cracks next year, buying the same model from a new batch will result in a color mismatch.
Future Plumbing Access:
If a shower valve leaks, a plumber will need to break 2–4 tiles to access the wall. Attic stock allows you to replace them seamlessly.
Discontinued Models:
Tile lines are discontinued frequently. If you don't save spares, you may have to rip out the entire floor over one cracked tile.
Worked Calculation Examples
See how overage rates translate into actual box counts for typical home remodeling projects.
Standard Bathroom Floor (60 sq ft)
Layout: Straight Lay Grid
Rate: 10% overageCalculated Area: 60 + 6 = 66 sq ft
Total to Buy: 66 tiles (if 12×12"), or 4 full boxes (at 17 sq ft/box)
Kitchen Backsplash (40 sq ft)
Layout: Herringbone Subway
Rate: 18% overageCalculated Area: 40 + 7.2 = 47.2 sq ft
Total to Buy: 189 subway pieces (if 3×6"), or 6 full boxes (at 8 sq ft/box)
L-Shaped Living Room (240 sq ft)
Layout: 12×24" 1/3 Offset Stagger
Rate: 15% overageCalculated Area: 240 + 36 = 276 sq ft
Total to Buy: 138 plank tiles, or 18 full boxes (at 16 sq ft/box)
When is Buying an Extra Box Justified?
Close to boundary lines
If your square footage calculation lands close to a box limit (e.g., needing 4.9 boxes), always buy the next full box. Never attempt to get by on exact numbers.
Natural Stone / Slate
Natural materials contain high variations in color and thickness. An extra box lets you throw away poor or damaged pieces before installing.
Special trims / corners
Bullnose edge tiles, corner caps, and listellos are sold individually. Order 2–3 extra of each trim tile, as these are highly prone to breakage.
Marcus Sterling
Certified Master Tile Installer & Technical Estimator
This guide has been technically reviewed and approved by Marcus Sterling. Marcus has over 20 years of hands-on experience in residential and commercial tile setting. He is a certified installer specializing in moisture diagnostics, deflection analysis, complex layouts, and estimation accuracy.
Overage FAQs
Answers to common tile ordering and overage padding questions.
Is 10% extra tile always enough?▼
No. 10% is sufficient for simple layouts (straight grid, horizontal running bond) in standard rectangular rooms done by a professional installer. If you are doing a DIY install, using large-format tile, layouts like herringbone/diagonal, or have an L-shaped room, increase your overage to 15% or 20%.
Should I buy an extra box of tile?▼
Yes, in most cases. If your total square footage requirement lands close to a box limit, round up to the next full box. Having half a box of tiles leftover is highly recommended to save as attic stock for future repairs, dye-lot matching, or valve repairs.
How many extra tiles are in a standard overage box?▼
It depends on the tile size. A box of 12×24 tiles typically contains 8 pieces (16 sq ft). A box of 3×6 subway tiles can contain 80 pieces (10 sq ft). Always check the box coverage square footage on the product specification before ordering.
What is attic stock and where should I store it?▼
Attic stock is the spare tile saved after installation. Store it in a dry location like a closet, garage shelf, or crawlspace. Save at least 10–15 pieces of field tile and 2–3 pieces of trim/bullnose tile to match dye lots for future plumbing work or cracks.
What happens if I run out of tile during installation?▼
Running out of tile is a major problem. If you order more of the same tile weeks later, it will likely come from a different manufacturing batch (dye-lot). Different dye-lots can have visible differences in color tone, size, and sheen, making patches highly visible.