Question 1

How many tiles do I need for a 10×10 room?

Accepted Answer

A 10×10 room is 100 sq ft. With 12×12 inch tiles and a 10% waste factor, you need 110 tiles. Switch to 18×18 tiles and that drops to about 49. The tile size matters more than people expect once you account for cuts. Our calculator adjusts the count for whichever size you choose.

Question 2

How much waste should I add when buying tile?

Accepted Answer

10% covers most straight-lay jobs in rectangular rooms. Diagonal layouts need 15% because the corner cuts waste more of each tile. For herringbone or chevron, budget 15 to 20%. Small mosaic tiles also run closer to 15% since there's more perimeter per square foot. Our calculator sets the default based on your layout choice, and you can override it if you know your room is tricky.

Question 3

How do I calculate tile for a diagonal layout?

Accepted Answer

The math is the same as straight lay, but the waste factor goes up to 15% instead of 10%. Every edge row has to be cut at a 45-degree angle, and those cut-off corners can't be reused. The additional tile cost is real, but a diagonal layout can make a small room feel larger, so it's often worth it.

Question 4

Should I add extra tile for future repairs?

Accepted Answer

Buy extra and keep a box. Tile patterns and dye lots change constantly, and a cracked tile a few years from now is nearly impossible to match if the product has been discontinued. A sealed box in the garage costs almost nothing compared to the hassle of tearing out a section because you can't find a match.

Question 5

How do I calculate tile for an L-shaped or irregular room?

Accepted Answer

Break the space into rectangles, measure each section, and use the Add Another Area button to total them. The waste factor applies across the combined area, which is accurate for most projects. For rooms with a lot of angles or obstacles, round your area estimates up rather than down.

Question 6

How many tiles come in a box?

Accepted Answer

It varies by size and manufacturer. Small tiles might have 80 to 100 per box; large format tiles might have 3 or 4. The box will always list coverage in square feet, which is the number to use. Divide your total square footage (with waste included) by the coverage per box to get your box count.

Question 7

Do I need to include grout joints in my calculation?

Accepted Answer

For most tile sizes, no. Standard 1/16 to 1/8 inch joints on 12-inch and larger tile have a negligible effect on the total tile count. The waste factor already covers the minor area difference. Where this matters is very wide grout joints on large format tile, and even then the impact on tile count is small.

Question 8

What's the formula for calculating tile?

Accepted Answer

Total sq ft equals length times width for each area. Sq ft to buy equals total sq ft times one plus your waste percentage. Tiles needed equals sq ft to buy divided by the tile's square footage, rounded up. Tile sq ft equals tile width in inches times tile height in inches divided by 144.

Layout Type	Recommended Waste	Why
Straight (grid)	10%	Minimal edge cuts, simple pattern
Diagonal (45°)	15%	Corner cuts waste more tile
Herringbone / Chevron	15–20%	Angle cuts on every piece
Small mosaic (under 4 in)	15%	More perimeter cuts per sq ft
Irregular or complex room	15–20%	Extra cuts around obstacles

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