Laminate Flooring Calculator

A 15 × 12 ft room is 180 sq ft; with 10% waste that is 198 sq ft, or 11 boxes of Pergo Outlast+ at 19.63 sq ft per box. The box count is the easy part. Laid across the 12 ft width, 7.48 in planks leave a last row only 1⅛ in wide, too thin to click in and hold; rip the first row to 4 5⁄16 in and both edge rows come out the same.

How the laminate calculator works

Boxes come from area: length × width, plus the waste allowance, divided by the coverage on the box and rounded up. The layout comes from the room width. Take off the expansion gap at both walls, divide by the plank's face width, and round up to get the number of rows. Whatever is left for the last row is the width you will rip.

rows = (room width − 2 × gap) ÷ plank width, rounded up

last row = (room width − 2 × gap) − (rows − 1) × plank width

balanced edge rows = (last row + plank width) ÷ 2

If the last row would be narrower than your limit, the calculator splits the difference between the first and last row. The drawing then lays every row plank by plank: each row starts with the longest offcut that keeps the end joints far enough from the row before, and a fresh plank is cut only when no offcut works.

Worked example: 15 × 12 ft bedroom in Pergo Outlast+

• Area: 15 ft × 12 ft = 180 sq ft. With 10%: 198 sq ft ÷ 19.63 = 10.1, so 11 boxes.
• Covered width: 144 in − 2 × ⅜ in = 143¼ in. Rows: 143.25 ÷ 7.48 = 19.2, so 20 rows.
• Last row as it falls: 143.25 − 19 × 7.48 = 1⅛ in, below the 2 in limit.
• Balanced: (1.13 + 7.48) ÷ 2 = 4.305 in. Rip the first row to 4 5⁄16 in; the last row ends up the same.
• Row by row with a 12 in stagger and no piece shorter than 8 in, the room takes 77 planks, which is 10 boxes of 8. The eleventh box from the 10% allowance covers damaged planks and cutting mistakes.
• Underlayment: 180 sq ft ÷ 100 sq ft per roll = 2 rolls.

The same room in LifeProof vinyl plank, 8.7 in wide with a ¼ in gap, has 17 rows and a 4.3 in last row, so nothing needs ripping, and 10 boxes at 20.1 sq ft.

Last row width for common plank widths

In a 12 ft wide room with a ⅜ in gap at each wall (143¼ in to cover):

A difference of ¼ in in room width can flip a row from comfortable to a sliver, so measure the width at both ends and in the middle, and use the smallest.

How narrow can the last row of laminate be?

Pergo says the last plank should be at least 5 cm (about 2 in) wide, and LifeProof treats a last row of 2 in or less as a special case you click to the row before and install together. That is why the default limit is 2 in. Narrow rows are fragile at the lock, and they look like a mistake at the wall you see most. Ripping the first row also takes the tongue off the wall side, which Pergo's instructions do for the first row anyway.

Expansion gap and stagger

Pergo Outlast+ asks for a ⅜ in gap on all sides, a first piece of at least 8 in, and at least 12 in between end joints in neighbouring rows. LifeProof asks for ¼ in, 8 in pieces and a 6 in stagger. The preset fills these in; change them to match your own box. Pergo also starts each new row with the piece cut from the end of the previous row, which is where the offcuts in the drawing come from. Floors longer or wider than 40 ft need a T-molding across them (Pergo).

Underlayment

Planks without an attached pad go over a foam underlayment, butted and taped at the seams; over concrete, Pergo adds a 6 mil polyethylene vapor barrier. Planks with an attached pad take no second acoustic layer on a wood subfloor. Switch the toggle off for attached-pad planks.

What to do next

• Several rooms, or hardwood in the hall? The flooring calculator adds them up by carton.
• The gap is hidden by baseboard or quarter round: count it with the baseboard calculator.
• For the installed price with removal of the old floor, use the flooring cost calculator.
• A bedroom in carpet instead: the carpet calculator.

Every floor and trim tool is on the floors, tile and trim page.