How many boxes of flooring?

Buy the extra box now, not later

The arithmetic is the easy part: room area divided by the coverage printed on the box, plus an allowance, rounded up. A 12 by 15 foot room is 180 ft², and at 20 ft² per box with 10% waste that is ten boxes.

The allowance is not padding. Laminate and vinyl plank are laid in rows, and the offcut from the end of one row can only start the next row if it is long enough — most instructions call for at least 8 to 12 inches, otherwise the seams line up too closely and the floor looks wrong. The pieces that fall short go in the bin. 10% covers a straight lay in a rectangular room; use 15% for a diagonal layout or a room with several doorways and angles.

Buy it all at once, and buy it from the same batch. Laminate is printed, and the print run shifts between batches — a box bought two months later can be visibly different in tone under daylight. The box carries a batch or lot number; check that they match before you leave the store.

Keep the leftovers. A spare plank or two is what lets you swap a damaged board in three years, and by then the exact product will almost certainly be discontinued. It is the cheapest insurance in the whole job.

A worked example: two bedrooms and a hallway

Flooring often runs through several rooms without a break. Say a 12 × 14 bedroom, an 11 × 12 bedroom and a 3 × 15 hallway get the same floor: 168 + 132 + 45 = 345 ft². With 10% waste that is 380 ft², so at 20 ft² per box you need 19 boxes. Hallways eat more material than their area suggests, because the rows are short and each one ends in a cut; if your layout has a long narrow hall, 12 to 15% is safer.

Laying one continuous floor through doorways looks best, but floating floors have a limit on how long a run can be without an expansion break. Check the instructions: past the maximum length, or at most doorways between rooms, you need a transition strip, and that changes your shopping list.

Waste by layout

Laminate or vinyl plank?

Mistakes that cost money

• Skipping acclimation. Most makers want the boxes in the room for 24 to 48 hours before installation. Planks laid straight from a cold truck move later.
• Not checking the subfloor. Floating floors need a flat base; dips of more than about 3/16 inch over 10 feet usually need leveling first. Check the maker's tolerance.
• Short end pieces. Keep the first and last plank in each row at least 8 to 12 inches long, and stagger end joints. A pattern of short pieces looks wrong and weakens the floor.
• Pinning the floor. Nailing baseboard or cabinets through a floating floor stops it moving and it buckles. Nail trim to the wall, not the floor.

What it costs

Laminate commonly sells for about $1.50 to $4 per square foot in the US, and luxury vinyl plank about $2 to $6. For the 380 ft² in the example, that is roughly $570 to $1519 in laminate, plus underlayment, transitions and quarter round. Prices vary by brand and thickness.