Example: a 15 × 12 ft living room
- Floor area: 15 × 12 = 180 sq ft.
- Add 10% for cuts and waste: 198 sq ft.
- Boxes: 198 ÷ 20 sq ft per box = 9.9, so buy 10 boxes.
- If the floor needs underlayment: 2 rolls of 100 sq ft.
How it's calculated
- Floor area = length × width. For L-shaped rooms, add up rectangles and use Total area.
- Add the waste allowance: area × 1.10 for 10%.
- Boxes = total ÷ coverage per box, rounded up.
Assumptions
- 10% extra by default for end cuts, mistakes and boards with defects.
- Underlayment: floor area + 5% for overlaps, in 100 sq ft (or 10 m²) rolls. Skip it if your flooring has a pad attached.
- Transition strips, baseboards and quarter round aren't included.
Frequently asked questions
How much extra flooring should I buy?
10% for most laminate, vinyl plank and hardwood jobs. Go up to 15% for diagonal or herringbone layouts or rooms with lots of angles. Only simple rectangular rooms with an experienced installer get away with 5%.
How do I work out how many boxes of flooring I need?
Divide the total square footage (including waste) by the coverage printed on the box, then round up. For example, 198 sq ft ÷ 20 sq ft per box = 9.9, so 10 boxes.
Should I include closets and doorways?
Yes — measure every area that gets the same floor, including closets and the space under doors, and add them together.
Do I need underlayment?
Most floating laminate and engineered floors need underlayment unless one is pre-attached, and many vinyl planks have a built-in pad. Over concrete a vapor barrier is usually required. Follow the manufacturer's instructions.
Should I keep leftover boxes?
Yes. Keep at least one unopened box — if a board gets damaged years later, a matching replacement is often impossible to find.