Tile Calculator
Area in — tile count, box count and cost out, with the waste factor and box size the big-box estimators bury.
The short answer
Formula. Tiles = floor area × 144 ÷ (tile width × tile height, in inches) × (1 + waste %), rounded up; boxes = tiles ÷ tiles-per-box, also rounded up.
Example. A 10 ft × 10 ft floor in 12×24-in tile with 10% waste needs 55 tiles — ten boxes of six, with five tiles spare.
How this calculator works
The count itself is honest division. Your area in square feet × 144 gives square inches; each tile covers its width × length in square inches; divide, and that is how many tiles cover the room with zero cuts. No room has zero cuts, so the waste factor — 10% for straight lay in a simple room, 15% for diagonal or herringbone where nearly every edge tile is cut twice — inflates the area before dividing. A 10 × 10 ft bathroom at 10% waste with 12 × 24 tile: 110 sq ft ÷ 2 sq ft per tile = 55 tiles.
The box line is what generic area math misses and what actually matters at the register, because tile is sold by the box, and tiles-per-box varies wildly with size — a 12 × 12 often comes 10 to a box, a 12 × 24 typically 6, planks a dozen or more. Boxes round up (the store will not open one for you), so 55 tiles at 6 per box is 10 boxes, 60 tiles, five spare. Those spares are not waste: dye lots change between production runs, so buy the whole job at once from the same lot number, and store one finished box in the garage for repairs a decade from now.
Two realities the arithmetic hides. Grout joints are deliberately ignored — the waste factor absorbs the hair of width they cost you. And layout quality is worth more than extra tiles: snapping a chalk line down the room's centerline and dry-laying the first course, shifting it half a tile if the cuts at the walls fall under 2 inches (slivers look terrible and crack), is the difference between a professional floor and a loud one. Complex borders, niches and accent strips should be measured as separate areas and summed before you start.
Sources & review date
- Waste allowances: 10% is standard for straight-lay patterns, 15%+ for diagonal or herringbone; tiles-per-box varies by manufacturer and is an input.
Last reviewed: October 2026. Numbers that drift (fees, prices, densities) are editable inputs on this page.
Tile FAQs
How many boxes of tile do I need?
Tiles needed (area with waste ÷ tile coverage), divided by tiles per box, rounded up. The calculator does exactly that — and always ends with one partial box as built-in spares.
How do I tile around a toilet, vanity or doorways?
For small penetrations, do nothing — the 10% waste covers them. For a big vanity or island you will never tile under, subtract its footprint from the area first. Doorway thresholds count as a few extra cut tiles; the waste factor handles them.
Should I buy extra tile for repairs?
Yes — deliberately. Keep one full box after installation. Ten years later, when two tiles crack, a matching dye lot will not exist; the spare box is the only insurance.
Does large-format tile need more waste?
In small rooms, yes — 12×24 and 24×24 tile in a narrow bathroom generates long cuts and more offcuts, so run 15%. Big open floors with the same tile need less, 10% is comfortable.