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Tile Calculator
Tile is sold by the box but laid by the piece, and cuts eat more than people expect. Enter your area and tile size to get the exact tile count, the count with a waste allowance for cuts and breakage, and the boxes to buy.
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Shopping list — buy this much
Keep the leftover tiles from the last box. A cracked tile five years from now is a five-minute repair if you have a spare from the same dye lot — and an exact match is nearly impossible to buy later.
How it works
Tiles = area ÷ tile area × (1 + waste %)
Boxes = tiles ÷ tiles per box, rounded up
The waste allowance is doing real work here. Every edge tile is a cut, cuts break, and large-format tiles in small bathrooms can waste a quarter of every other piece. 10% suits a straight grid in a rectangular room; go 15% for diagonal layouts, offsets and patterns; 20% for mosaics and rooms with many obstacles. Grout joints slightly reduce the tile count on big floors, but at standard 3/16 in joints the difference is under 2% — inside the waste factor, so this calculator ignores it rather than pretending to false precision.
Thinset and grout are separate materials with their own math: thinset runs roughly 75–95 sq ft per 50 lb bag with a 1/4 in trowel (less for large-format), and grout depends on tile size and joint width. The grout calculator is on our build list — see the related links.
Worked example
A 10×10 ft bathroom floor is 100 sq ft. With 12×12 in tiles (exactly 1 sq ft each), that's 100 tiles before waste; at 10% waste, 110 tiles; at 10 tiles per box, 11 boxes — $495 at $45 a box. Change the tile to 24×12 in planks (2 sq ft each) and the same floor needs 55 tiles with waste — fewer, bigger, and faster to lay, but each cut wastes more, which is why the waste field is yours to set.
Frequently asked questions
How many tiles do I need for 100 square feet?
It depends on tile size. With 12x12 in tiles (1 sq ft each): 100 tiles, 110 with a 10% waste allowance. With 6x6 in tiles (0.25 sq ft each): 400 tiles, 440 with waste. Divide your area by the tile's area in square feet, then add waste.
How much extra tile should I buy for waste?
10% for straight layouts in rectangular rooms, 15% for diagonal, offset or herringbone patterns, and up to 20% for small rooms with lots of cuts or large-format tile. Pros also keep a few spares from the same dye lot for future repairs.
Does grout joint width change the tile count?
Slightly. A 3/16 in joint means each tile plus its share of joint covers a bit more than the tile alone, reducing the count by roughly 2% on a big floor. That difference sits comfortably inside the waste allowance, so estimating from tile size alone is standard practice.
How many tiles come in a box?
It varies by size and brand: commonly 10–20 for 12x12 floor tile, 4–6 for large-format 24x24 or plank tile, and sheets of mosaic are counted individually. The box prints its coverage in square feet — tiles per box here should match the box you're actually buying.
How do I measure a floor for tile?
Length × width for rectangles; split L-shaped floors into two rectangles and add them (our square footage calculator has a project total for exactly this). Measure the longest points and round up to the nearest inch — floors are rarely perfectly square, and being short one box mid-job means a trip back and a possible dye-lot mismatch.
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About the author
Harrison Alley is a web publisher and data enthusiast based in Dallas, Texas. He built Urbarama’s remodeling calculators and maintains them.
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