Crunch Flooring Calculator
Flooring is sold by the box and wasted by the cut. Enter the room (or a total area), the coverage printed on the box, and your waste allowance, and get the box count and the real material cost — before the store does the math for you.
Waste guide: 5% for a plain rectangle laid straight, 10% standard, 15% for diagonal layouts, small rooms or lots of cuts. Keep one spare box after the job — a discontinued line is unmatchable later.
How it works
Area first: room length × width, or your own total for multi-room jobs. The buy quantity is area × (1 + waste %) — offcuts at walls, mistakes and pattern matching — divided by the box coverage and rounded up to whole boxes. Cost is boxes × box price; the per-sq-ft line lets you compare products sold in different box sizes honestly.
Formula & worked example
Formula: Buy quantity = floor area × (1 + waste %) ÷ box coverage, rounded up to whole boxes; cost = boxes × box price. The waste allowance covers end cuts, mistakes and pattern matching that a bare area ÷ coverage division ignores.
Worked example: A 12 × 10 ft room is 120 sq ft; with 10% waste you buy for 132 sq ft, and at 20 sq ft per box that is 7 boxes — about $315 at $45 a box, or $2.63 per sq ft of floor. At 5% waste the count is still 7 boxes here: box rounding swallows the difference.
Frequently asked questions
How many boxes for a 12 × 10 room?
The room is 120 sq ft. With 10% waste you buy for 132 sq ft; at 20 sq ft per box that is 7 boxes — about $315 at $45 a box. Straight-lay at 5% waste would take 6.3 → also 7 boxes here, which is common: box rounding swallows small waste differences.
How much waste should I allow?
Five percent for a simple rectangle with planks run straight; ten as the safe default; fifteen for diagonal or herringbone layouts, rooms with many angles, or first-time installers. The cost of one extra box is trivial next to a mid-job stock-out in a different dye lot.
Why not just divide area by box coverage?
Because almost every row ends in a cut, and the cut-off piece only sometimes starts the next row. Real installs consume 5–15% more material than the floor’s area — the waste allowance is that reality, priced in advance.
Does the calculator work for tile or hardwood?
Yes — anything sold by coverage per box: laminate, LVP, engineered hardwood, ceramic tile. For tile with grout joints, the Tile Calculator also counts by grid, which catches edge cases a coverage count can miss.
🧱 Walls after the floor?
The Drywall Calculator counts sheets and screws for the same room — finish the materials list in one sitting.