Flooring & Tile
Flooring Calculator
Enter your room dimensions in feet to get the square footage of flooring to buy, the number of boxes, and an editable cost estimate for vinyl plank or laminate, with a wastage allowance for cuts and spares.
Formula tested · Local units · No sign-up
Project inputs
Enter measurements
Use your preferred units. Results update automatically.
Show the calculation methodFormula, conversions, rounding, and assumptions+
Room area = length × width in square feet — a 12 ft × 10 ft room is 120 sq ft. For L-shaped rooms, add the rectangles and use direct-area mode.
A wastage allowance is added on top (default 8% for a straight plank lay; more for diagonal or herringbone), then the total is divided by the coverage printed on the box — commonly around 20 sq ft per box for laminate or vinyl plank — and rounded up to whole boxes, because flooring is sold in sealed boxes.
Real-world example
Worked example: 12 ft × 10 ft bedroom, vinyl plank, 8% wastage
- Room area: 12 × 10 = 120 sq ft.
- Add 8% wastage: 120 × 1.08 = 129.6 sq ft to purchase.
- Boxes at 20 sq ft per box: 129.6 ÷ 20 = 6.48.
- Round up to whole boxes: 7 boxes.
Buy 7 boxes (140 sq ft). Cost estimate: 7 × your supplier's price per box, then add your local sales tax rate to that subtotal.
Before you start
How to measure
- Measure the room's length and width in feet at the longest and widest points, including closet floors and doorway thresholds the flooring will run into.
- Take the coverage per box straight from the box label — it varies by plank size and brand, so the ~20 sq ft figure is only a typical starting point.
- For rooms with angles or multiple alcoves, split the floor into rectangles, add the square footage, and enter it in direct-area mode.
Local guidance
Notes for United States
- US flooring is priced per square foot but sold by the box; the box label states both the sq ft coverage and the plank dimensions.
- Vinyl plank (LVP), laminate and engineered hardwood dominate the DIY market; solid hardwood is usually sold by the sq ft through specialty suppliers.
- Sales tax varies by state and locality and is entered manually; big-box shelf prices are per sq ft before tax, so multiply by the box coverage to compare with a per-box quote.
Quick reference
Typical wastage allowance by laying pattern (planning values)
| Pattern | Typical allowance |
|---|---|
| Straight lay, regular room | 8% |
| Straight lay, many doorways/alcoves | 10% |
| Diagonal lay | 12–15% |
| Herringbone / chevron | 15–20% |
Planning values only — your installer and the room's shape determine the real allowance.
Good to know
Common mistakes to avoid
- Ordering the exact room area with no wastage — every row ends in a cut, and you'll want matching spares for future repairs.
- Comparing a per-sq-ft price against a per-box price without multiplying by the box coverage.
- Forgetting closets, pantries and doorway transitions when measuring.
- Using the straight-lay allowance for a herringbone pattern that consumes far more in angled cuts.
Need help?
Frequently asked questions
How many boxes of flooring for a 15 × 12 room?
15 × 12 = 180 sq ft; with 8% wastage that's 194.4 sq ft. At 20 sq ft per box, 194.4 ÷ 20 = 9.72, so buy 10 boxes — and check your actual box coverage, which varies by product.
How much extra flooring should I buy?
8% is the usual planning allowance for a straight lay in a regular room; go to 10% with many doorways or alcoves and 15% or more for diagonal or herringbone patterns. Unopened boxes can often be returned — keep a few spare planks either way.
Does this include underlayment?
No — underlayment is sold separately by the roll (some plank products have it pre-attached). This calculator estimates the flooring itself; the same square footage tells you how much underlayment to buy.
Keep planning
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About this calculator
- Written by:
- BuildMeasure Editorial Team
- Technically reviewed by:
- Pending independent technical reviewer (formula unit-tested; see methodology)
- Last reviewed:
- 2026-07-16
- Formula version:
- 1.0.0
- Region reviewed for:
- United States
- Spotted an error?
- Report a correction
Methodology
- Room area comes either from length × width or from a directly entered area. All arithmetic runs internally in SI units (m²); regional units (feet, ft²) are converted exactly on the way in and out.
- The area to purchase = room area × (1 + wastage %). Wastage covers end-of-row cuts, defects and spares, and depends mainly on the laying pattern — the default 8% suits a straight plank lay.
- When you enter the coverage per box from the box label, boxes = purchase area ÷ box coverage, rounded UP to a whole box, because flooring is sold in sealed boxes.
- The cost estimate uses the price you enter: price per box × boxes when a box price is given (it takes precedence), otherwise price per area × the purchase area; the tax rate you enter is then applied. No prices are built in.
- The formula is covered by automated unit tests, including hand-calculated worked examples, and is versioned (see formula version on this page).
Sources & standards
- Unit definitions: 1 ft² = 0.09290304 m² (exact definition).
- Wastage allowances: 8% straight lay / 15%+ herringbone are standard planning allowances; confirm with your installer.
This tool provides a material estimate for planning purposes only. It is not a quotation, and it does not cover underlay, trims, subfloor preparation or installation. Confirm quantities and box coverage with your flooring supplier before ordering.