How much flooring to buy
Laminate, vinyl plank and engineered hardwood are sold by the box, and every box covers a fixed number of square feet. To avoid a second trip, or a box that no longer matches, you need the floor area, a waste factor for your layout, and the coverage printed on the box.
The formulas
- Floor area = length × width. For an L-shaped room, split it into rectangles and add them.
- Flooring to buy = area × (1 + waste factor).
- Boxes = flooring to buy ÷ coverage per box, rounded up.
- Baseboard = room perimeter − door openings, plus 10% for miter cuts.
Worked example: a 15 × 12 ft bedroom
- Area: 15 × 12 = 180 sq ft.
- With a 10% waste factor: 198 sq ft.
- At 20 sq ft per box: 198 ÷ 20 = 9.9, so 10 boxes, or 200 sq ft.
- At $3.50 per square foot, the flooring costs $700.
- Underlayment: 2 rolls of 100 sq ft.
- Baseboard: 2 × (15 + 12) − 3 = 51 ft, or 8 pieces of 8 ft.
Waste factor by layout
| Layout | Waste | Boxes for 180 sq ft |
|---|---|---|
| Straight, rectangular room | 5% | 10 |
| Straight with cuts | 10% | 10 |
| Diagonal | 15% | 11 |
| Herringbone or chevron | 20% | 11 |
Rooms with many closets, angles or obstacles sit at the high end of each range. Long, wide planks also produce longer offcuts, which are harder to reuse.
Before you install
- Acclimate wood and laminate in the room for about 48 hours in closed boxes.
- Check the subfloor: it must be flat, typically within 3/16 in over 10 ft for floating floors. Fill dips and sand high spots.
- Leave an expansion gap of about 1/4 to 1/2 in along the walls for floating floors. The baseboard or quarter round hides it.
- Mix boxes as you lay, to blend small color differences between batches.
Underlayment
Most laminate needs foam or felt underlayment, plus a vapor barrier on concrete. Many vinyl planks and some laminates have an attached pad, and adding a second layer can void the warranty. Set the roll coverage to 0 in that case.
Keep a spare box
A floor damaged by water or a dropped pan is easiest to repair with planks from the same batch. A leftover box, stored flat, is worth far more than its price five years later, when the product may be discontinued.