Understanding your result
The headline is the boxes to buy; the stats add the floor area, the area to order and either the plank count or the spare. The table runs from the area through the waste to boxes and flooring bought, then the planks (boxes times planks per box) and the underlayment, which is either a roll count or “attached pad, none needed”.
Boxes is the area to order divided by the box coverage, rounded up. The coverage is the figure that varies most between brands, which is why it is the first input after the room. Planks is a convenience: the number of pieces you will handle, useful for the plank layout calculator and for judging the box count against the planks in the sample you took home.
Underlayment is counted at 5% over the room area, enough for trimming with butted seams; the underlayment calculator goes further with roll widths, seam tape and a vapor barrier for a slab. If the laminate has an attached pad, the row says so and nothing is counted, because a second cushion is a mistake the notes explain. The expansion gap and the run limit that go with any floating floor are on the expansion gap calculator; the same arithmetic for vinyl plank is on the vinyl plank calculator.
How we calculate this
Waste follows the layout, from the table on the waste factors reference: 10% straight, 15% diagonal, 20% herringbone. Laminate has no grade waste to add, because the planks are printed and identical, though some patterns repeat a few faces and need a little extra to avoid two identical planks side by side; the guide to buying click plank explains the pattern-repeat trap, which applies to laminate as much as vinyl. The underlayment guide covers the foam, felt and combined products and when each is right.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Box coverage | 19.6 sq ft (1.8 m²) | Pergo Outlast+ 7.5 × 48 in, 8 planks per box; Mohawk RevWood is 19.63, Shaw Repel 22.09, TrafficMaster 17.26 (manufacturer product pages, 2025) |
| Planks per box | 8 | Typical for 7 to 8 in wide planks; 10 for narrower planks |
| Waste | 10 / 15 / 20% by layout | Industry rule of thumb, see the waste factors page |
| Underlayment allowance | 5% | Trimming at the walls with butted seams |
| Underlayment roll | 100 sq ft (10 m²) | Standard foam roll; 200 sq ft rolls are common |
| Run limit warning | 40 ft | Most laminate makers specify a T-moulding at 30 to 40 ft of unbroken run (installation instructions, Pergo and Mohawk) |
Assumptions last reviewed October 8, 2026.
The calculator does not lay the planks out, so it cannot say how wide the last row will be or whether the first row should be ripped; the plank layout calculator does that from the room width and the plank width. It does not count the transition strips at doorways, the baseboard or quarter round that hides the expansion gap, or the vapor barrier over concrete, each of which has its own calculator in the measuring and subfloor groups. And it assumes one product across the whole floor.
Two worked examples
A 16 × 11 ft bedroom with a separate underlayment
Boxes of 20.4 sq ft and 8 planks at $35, straight layout, 100 sq ft underlayment rolls.
- Floor area: 16 × 11 = 176 sq ft; with 10%: 194 sq ft
- Boxes: 194 ÷ 20.4 = 9.5, rounded up to 10 boxes (204 sq ft), $350
- Planks: 10 × 8 = 80; spare 28 sq ft
- Underlayment: 176 × 1.05 = 185 sq ft ÷ 100 = 1.85, rounded up to 2 rolls
Ten boxes and two rolls. The 28 sq ft spare is a box and a bit, enough for the repair that a dropped iron will one day demand. Eighty planks in a 16 ft room is 11 rows of about 7 planks, which the plank layout calculator can check for the last-row width.
A 640 sq ft open-plan floor, attached pad, diagonal
Area typed directly, boxes of 17.26 sq ft and 8 planks at $28, diagonal layout.
- Area to order: 640 × 1.15 = 736 sq ft
- Boxes: 736 ÷ 17.26 = 42.6, rounded up to 43 boxes (742 sq ft), $1,204
- Planks: 43 × 8 = 344; spare 102 sq ft
- Underlayment: attached pad, none
Forty-three boxes of a small-coverage product for a floor that would take 36 boxes of a 20 sq ft product: the label matters more than the price per box. A 640 sq ft open plan is also likely to exceed the maker’s run limit in one direction, so the T-moulding question belongs in this order.
Where to find your inputs
Box coverage and planks per box. Both are printed on the box end and on the product page. Enter them exactly; 19.6 is not 20.
Room or area. Wall to wall, including closets and under doorways. For an L-shaped plan, the floor area calculator adds the rectangles.
Attached pad. The box says “pad attached”, “pre-attached underlayment” or similar. If it does not, assume there is none.
Underlayment roll coverage. On the roll: 100 or 200 sq ft for most foam and felt.
Common mistakes
- Assuming 20 sq ft a box. Coverage runs from 17 to 25 for ordinary laminate. Read the box.
- Foam under an attached pad. Two cushions break the click joints. One or the other.
- No vapor barrier on a slab. Plain foam is not a vapor barrier; use a combined product or a 6 mil sheet beneath.
- Pinning the floor. Baseboard, cabinets or a nailed transition strip through the planks stop the floor moving and it buckles.
- Ignoring the run limit. Past 30 to 40 ft a floating floor needs a T-moulding. Check the carton.
- Skipping the acclimation. Laminate needs 48 hours in the room, boxes flat and unopened, before it is laid.
Questions people ask
- How many boxes of laminate for a 12 × 12 room?
- A 12 × 12 ft room is 144 sq ft; with 10% waste that is 158.4 sq ft. At 19.6 sq ft per box (Pergo Outlast+) it is 8.1 boxes, so you buy 9; at 17.26 sq ft per box (TrafficMaster) it is 9.2, so 10; at 22.09 (Shaw Repel) it is 7.2, so 8. The label decides.
- How many square feet are in a box of laminate?
- Between about 17 and 32 sq ft, most often 18 to 25. Eight planks of 7.5 × 48 inches is 19.6 sq ft; ten planks of 5.4 × 47.7 inches is 22 sq ft. The plank count and the coverage are both printed on the box.
- How much waste for laminate flooring?
- 10% for a straight layout in a plain room, 15% for a diagonal or a room with many doorways and angles, and 20% for herringbone with a herringbone-specific product. Laminate is click-locked and the offcut from the end of one row starts the next, so a straight layout rarely wastes more than 10%.
- Do I need underlayment under laminate?
- Yes, unless the planks have a pad bonded to the back. A foam or felt underlayment smooths the subfloor, quietens the floor and is required by most warranties; over concrete it must include or sit on a vapor barrier. Never put a second underlayment under an attached pad, because two soft layers let the joints flex and fail.
- Do I need a T-moulding in a long room?
- Most makers limit a floating laminate floor to 30 to 40 ft in any direction before an expansion break is needed, and to a similar total area. Beyond that a T-moulding divides the floor, usually at a doorway. The calculator notes when your longest dimension passes 40 ft; the expansion gap calculator gives the exact limit for your product.
- What is the difference between laminate and vinyl plank for quantities?
- Almost none in method, since both are boxes of click planks, counted the same way with the same waste. Vinyl plank boxes tend to cover more (18 to 32 sq ft), vinyl can go in wet rooms where laminate cannot, and vinyl plank needs a thinner underlayment or none. The vinyl plank calculator has its own defaults.