Tile Calculator

Tiling a bathroom or kitchen floor? You need to know how many tiles to buy — and you don't want to run short halfway through. This tile calculator figures out the exact count plus a waste allowance so you order the right amount the first time.

What Does This Calculator Do?

Enter your room dimensions and your tile size, and the calculator tells you how many tiles you need, including a recommended waste factor for cuts and breakage.

How to Use This Calculator

1. Enter the room length and width in feet.
2. Enter the tile size in inches (e.g., 12×12 or 18×18).
3. Select your waste factor — 10% for simple layouts, 15–20% for diagonal patterns.
4. Click Calculate to see the number of tiles and boxes needed.

Tile Formula

Room Area = Length × Width

Tile Area = (Tile Length ÷ 12) × (Tile Width ÷ 12) (converting inches to feet)

Tiles Needed = Room Area ÷ Tile Area × (1 + Waste Factor)

Example Calculation

You're tiling a 10 ft × 8 ft bathroom with 12×12 inch tiles, diagonal layout (15% waste).

• Room area: 10 × 8 = 80 sq ft
• Tile area: (12/12) × (12/12) = 1 sq ft per tile
• Tiles before waste: 80 ÷ 1 = 80 tiles
• Add 15% waste: 80 × 1.15 = 92 tiles
• If sold in boxes of 10: order 10 boxes

Why Use This Calculator?

Running out of tile mid-project is a real problem — dye lots change between batches, so replacement tiles may not match. Buying slightly more than you need is always the right call, and this calculator builds that buffer in automatically.

Common Mistakes to Avoid

• Not adding a waste factor — especially for diagonal layouts or rooms with many obstacles (toilets, vanities).
• Forgetting to measure in the same units — convert tile sizes and room sizes to the same unit before calculating.
• Ignoring grout lines — grout spacing slightly reduces coverage per tile. For standard 1/8-inch grout lines, the impact is minimal but worth noting.
• Buying from multiple lots without checking — always verify tiles from the same dye lot for consistent color.

Frequently Asked Questions

How many tiles do I need for a 100 sq ft room?

With 12×12 inch tiles, you need 100 tiles plus waste. Add 10–15% for a total of 110–115 tiles.

What waste factor should I use for diagonal tiles?

Use 15–20% for diagonal (45°) patterns due to the extra cuts required at walls and corners.

Do I measure walls or floor for shower tiles?

Measure each wall separately (length × height), add the totals, and subtract openings (windows, niches). Don't forget the floor.

How many sq ft does a box of tile cover?

It depends on the box. Check the label — most 12×12 tiles come 10–15 per box (10–15 sq ft). Larger tiles may be sold 4–6 per box.

Should I buy extra tile for repairs?

Yes. Always keep 5–10 extra tiles from the same lot for future crack repairs or replacements. Store them in a dry place.

Conclusion

Tile projects come down to accurate measurements and smart ordering. This calculator takes 30 seconds to use and can save you from multiple trips to the hardware store. Always buy a little extra — you'll thank yourself later.

Related: Square Footage Calculator | Grout Calculator | Flooring Calculator