How much flooring to buy
Floor area = length × width (+ closets and other areas)
Flooring to buy = floor area × (1 + waste %)
Boxes = flooring to buy ÷ coverage per box, rounded up
Flooring is sold in whole boxes, and every row needs cut pieces at the walls, so you always buy more than the floor area. Manufacturers and retailers usually recommend adding about 10% for a standard installation, more for diagonal or patterned layouts.
Worked example: a 15 × 12 ft living room
- Floor area: 15 × 12 = 180 sq ft (16.72 m²).
- With 10% waste: 180 × 1.10 = 198 sq ft.
- Laminate in boxes of 20 sq ft: 198 ÷ 20 = 9.9, so buy 10 boxes (200 sq ft).
- At 2.79 per sq ft, 10 boxes cost 200 × 2.79 = 558.00.
The same room laid in a herringbone pattern with 20% waste needs 216 sq ft, which is 10.8 boxes, so 11 boxes.
How much waste to allow
| Situation | Typical allowance |
|---|---|
| Square room, planks laid parallel to the long wall | 5–7% |
| Most rooms, a few corners and a doorway | 10% |
| Diagonal lay, many corners, hallways, stairs | 15% |
| Herringbone, chevron or patterned designs | 15–20% |
Keep one unopened box after the job. Batches vary in colour, and a matching spare is the easiest way to repair a damaged plank years later.
Different flooring types
- Laminate and luxury vinyl plank (LVP): sold in boxes, usually 18–25 sq ft each. Enter the box coverage exactly as printed.
- Engineered and solid hardwood: also by the box, often 20–30 sq ft. Leave a gap at the walls for expansion, as the manufacturer instructs.
- Carpet: sold from rolls, usually 12 ft wide, and often priced per square yard. Seams and pile direction can add more waste than plank flooring, so ask the store to plan the cuts. To compare prices, divide a per-square-yard price by 9 to get the price per square foot.
- Tile: counted by the piece; use the tile calculator.
Don't forget the extras
- Underlayment: the same area as the floor (without the waste allowance), unless the planks have it attached.
- Transition strips at each doorway where the flooring meets another floor.
- Baseboard or quarter-round: the room perimeter minus doorways. A 15 × 12 room has a perimeter of 54 ft.
Step by step: measuring for new flooring
- Sketch the room, including closets, alcoves and doorways the floor will run into.
- Measure the length and width of each rectangle at floor level, rounding up to the next inch or centimetre.
- Add the areas together and enter any extra rectangles as extra area.
- Choose the waste allowance for your layout and check the coverage printed on one box.
- Round the number of boxes up, and keep one spare box after the job.
Metric example
A room 4.5 × 3.6 m has an area of 16.2 m². With 10% waste you need 17.82 m². With boxes covering 2.2 m² each, 17.82 ÷ 2.2 = 8.1, so buy 9 boxes (19.8 m²).
Acclimating the flooring
Most laminate, vinyl plank and wood manufacturers ask you to leave the unopened boxes in the room for a period before installation, often 48 hours, so the boards adjust to its temperature and humidity. Check the instructions for your product, because skipping this step can void the warranty.
Common mistakes
- Buying exactly the floor area. Without waste you will run short on the last row.
- Rounding the boxes down. 9.9 boxes means 10 boxes.
- Forgetting closets and the area under doors, or measuring the room with the baseboards' thickness counted twice.
Frequently asked questions
How do I calculate how much flooring I need?
Multiply length by width for the floor area, add 10% for waste, then divide by the coverage of one box and round up. A 15 × 12 ft room is 180 sq ft, 198 sq ft with waste, so 10 boxes of 20 sq ft.
How much extra flooring should I buy?
About 10% for most rooms, 5% for a simple square room laid straight, and 15–20% for diagonal, herringbone or rooms with many corners.
How many boxes of laminate do I need for 500 square feet?
With 10% waste you need 550 sq ft. With boxes of 20 sq ft that is 27.5, so 28 boxes. Always check the coverage printed on your product.
How do I convert carpet price per square yard to per square foot?
Divide by 9, because a square yard is 9 square feet. Carpet at 27 per square yard costs 3 per square foot.
How many boxes of flooring do I need for 20 square metres?
With 10% waste you need 22 m². With boxes of 2.2 m², that is exactly 10 boxes; with boxes of 2.0 m², 11 boxes.
Sources
- Retailer and manufacturer installation guides for laminate and vinyl plank flooring (typical 10% overage; 15% or more for diagonal and patterned layouts).
- NIST Handbook 44 Appendix C: 1 square yard = 9 square feet; 1 square foot = 0.09290304 m².
Last reviewed 20 October 2026. Results are estimates; see our disclaimer.