Flooring Calculator
Flooring to buy is the net floor area plus a layout waste allowance — 10% straight, 15% diagonal, 20% herringbone — divided by the coverage per box and rounded up. A 200 ft² room laid straight needs 220 ft², or 11 boxes at 20 ft² each. Measure the room first with the Floor Area Calculator.
How it's calculated: Boxes = floor area × (1 + layout waste %) ÷ coverage per box, rounded up.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Area to buy = Floor area × (1 + layout waste %)
Boxes = Area to buy ÷ coverage per box, rounded up
Run the calculation to see each step with your own numbers.
200 ft² room, 20 ft²/box, straight lay.
Area to buy = 200 × 1.10 = 220 ft²
Boxes = ⌈220 ÷ 20⌉ = 11
- Net floor area (obstructions already removed).
- Waste percentage is set by the layout — straight 10%, diagonal 15%, herringbone/chevron 20%. Long narrow rooms and lots of doorways push it higher.
- Underlayment, transitions, trim and adhesive/fasteners are separate.
- Can I buy exactly the area of my room?
- No — always add for cuts, and keep an unopened box from the same production lot. Colour and finish shift between lots, so a later repair from a different lot is visible.
- How much extra should I buy?
- At least 10% over the room area for a straight lay, plus one unopened box from the same production run for future repairs.
- Why does the layout change the number so much?
- Diagonal and herringbone layouts produce more angled offcuts that can't be reused, so a bigger share of every box becomes waste. A long, narrow room with many doorways pushes it higher still.
- How many boxes of flooring do I need?
- Multiply the room's net floor area by 1.10 for a straight lay (1.15 diagonal, 1.20 herringbone), divide by the square feet per box printed on the carton, and round up. A 200 ft² room at 20 ft² per box needs 11 boxes.
Waste allowance
≈ 10% waste for a straight/grid tile or plank layout (cuts + breakage + attic stock). Tile Council of North America (TCNA) Handbook / NWFA guidance. Diagonal or pattern layouts 15%+. Editable.
Waste allowance — reference
About the Flooring Calculator
The Flooring Calculator turns a room's floor area into boxes of laminate, engineered wood, vinyl plank or solid hardwood, adding a cut allowance that depends on the layout — 10% for a straight or staggered lay, more for diagonal or herringbone. Enter the net area and the coverage printed on the carton. Underlayment, trim and transition strips are separate.
What you enter
- Floor area — Net floor area — use the Floor Area Calculator.
- Coverage per box (ft²) — Printed on the carton — commonly 18–24 ft² for laminate/plank.
- Layout
What you get back
- Area to buy — the exact result of the calculation.
- Boxes — the exact result of the calculation.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Floor Area Calculator — Total floor area of a room or a set of rooms.
- Tile Calculator — Tiles and boxes needed for a floor or wall, including an allowance for cuts.
- Plywood Calculator — Sheets of plywood or OSB for a floor, wall or roof area.
Part of the Tile & Flooring calculators.