How much flooring do I need?
Take the room area, add waste for the pattern, then divide by the coverage printed on the box and round up. A 20 × 14 ft room is 280 square feet; at 8% straight-lay waste that is 303 square feet, which at 24 square feet a box is 13 boxes.
Waste is not a single number. A straight lay in a rectangular room wastes about 8%. A 45-degree diagonal wastes 15% because every plank at the wall is cut twice. Herringbone wastes 20% or more, and that is before the labour difference.
Odd-shaped rooms, lots of doorways and narrow hallways all push waste up because there are more cuts and fewer usable offcuts. If the room has more than four corners, use the next waste bracket up rather than the one that matches your pattern.
How the calculation works
Square feet = length × width per room, minus permanent fixtures like an island base or a hearth. Do not deduct doorways — you floor through them, and the threshold cut comes out of waste.
Boxes are always rounded up, and the rounding is why the spare figure matters. If 303 square feet needs 12.6 boxes you buy 13, which leaves nearly half a box over. That is not waste, it is your repair stock.
Coverage per box varies by product far more than people expect — from about 18 to 30 square feet even within the same category. Never calculate boxes from a remembered figure; read the carton.
Underlayment is bought by actual floor area with no waste allowance, because it is a roll you cut to fit. Skip it only when the plank has pad pre-attached, and never double up — two layers of pad voids most click-lock warranties and makes the joints work loose.
Typical flooring cost, mid-2026
| Material | Unit | Typical range |
|---|---|---|
| Laminate | per sq ft | $1.50 – $4.50 |
| Luxury vinyl plank | per sq ft | $2.00 – $6.00 |
| Engineered wood | per sq ft | $4.00 – $12.00 |
| Solid hardwood | per sq ft | $5.00 – $15.00 |
| Underlayment | per sq ft | $0.30 – $0.90 |
| Transition strip | each | $15.00 – $45.00 |
| Installation labourDouble for herringbone | per sq ft | $2.00 – $6.00 |
| Subfloor levelling compound | per bag | $25.00 – $50.00 |
Check the subfloor before ordering anything. Click-lock floors need flatness within about 3/16 in over 10 ft, and levelling an out-of-flat floor is a separate job with its own budget.
What goes wrong on this job
- Buy every box in one order and check the batch numbers match. Colour and gloss shift between production runs, and a mismatched box always ends up in the middle of the living room.
- Open and mix from three or four boxes at once. Even within a batch there is plank-to-plank variation, and drawing from several cartons distributes it instead of banding the floor.
- Keep one full sealed box as repair stock. Products are discontinued constantly, and a damaged plank two years on is unfixable without it.
- Let wood acclimatise in the room in its boxes for the manufacturer stated period. Skipping it is why floors gap in January and buckle in July.
- Dry-lay the first three rows before you commit. It is the only cheap moment to find out the last row will be a 1 in sliver — shifting the start line by half a plank fixes it.
Frequently asked questions
How much waste should I add for flooring?
8% for a straight lay in a simple rectangular room, 15% for a 45-degree diagonal, and 20% or more for herringbone. Add a bracket for rooms with many corners or narrow hallways.
How many boxes of flooring for a 12x12 room?
144 square feet plus 8% waste is 156 square feet. At 24 square feet a box that is 7 boxes.
Do I deduct doorways from the flooring area?
No. You floor through a doorway and the threshold cuts come out of waste. Only deduct permanent fixtures like an island base or a hearth.
How much extra flooring should I keep?
At least one full sealed box. Products get discontinued and colour lots change, so a plank damaged later cannot be matched without it.
Do I need underlayment under vinyl plank?
Only if it does not have pad pre-attached. Doubling up on underlayment makes the joints flex and voids most click-lock warranties.