How flooring quantity is calculated
Area = length × width (add rooms separately)
With waste = area × (1 + waste %)
Boxes = with waste ÷ coverage per box, rounded up
A waste allowance covers end cuts, pattern matching and mistakes. There is no universal figure: installers commonly allow around 10% for a straight lay in a simple room, and more for diagonal or herringbone patterns and rooms with many corners. Follow the manufacturer’s installation instructions for your product.
Worked example
A 15 × 13 ft room, 10% waste, boxes covering 22.5 sq ft:
| Area | 195 sq ft |
|---|---|
| With 10% waste | 214.5 sq ft |
| Boxes | 10 (225.0 sq ft) |
Measuring tips
- Measure wall to wall at the widest points; include closets and areas under appliances that will be floored.
- For L-shaped rooms, split into rectangles and enter the total in “Or total area”.
- Buy all boxes from the same production lot so colors match, and keep a spare box for repairs.
Frequently asked questions
How much extra flooring should I buy?
A common allowance is about 10% for a straight lay, more for diagonal or patterned installs. Check your flooring manufacturer’s guidance.
Does this work for carpet?
For area, yes. Carpet is sold off rolls of fixed width (often 12 ft), so seams and roll width affect the amount; ask your retailer to plan the layout.