Laminate and Vinyl Plank Calculator

Boxes of plank flooring plus underlayment, transition strips, and a check on how wide the final row lands.

Draft — awaiting review. Not indexed.

Formula: Boxes = area × (1 + waste) ÷ coverage per box. Final row width = (room width − expansion gaps) modulo plank width.

What this calculates

This counts boxes of laminate or vinyl plank, and the things that have to be bought alongside them. A floating floor is not just the planks: it needs underlayment beneath, a transition strip at every doorway, and an expansion gap around the whole perimeter so the floor can move with humidity without buckling. It also works out how wide the last row will land, which is the detail that separates a floor that looks fitted from one that looks like it ran out. If you are laying tile rather than plank, the tile calculator is the better fit — it accounts for thinset instead of underlayment.

How it works

Boxes are the floor area plus a waste allowance, divided by the coverage printed on the box and rounded up. Underlayment is the plain area divided by the roll coverage, with no waste added, since it is trimmed rather than cut to pattern. The final row calculation subtracts the expansion gap from both walls, divides the remaining width by the plank width, and reports what is left over. That leftover is the width of the last row, and if it comes out under about an inch the usual fix is to trim the first row narrower so the difference is shared between the two walls rather than concentrated at one.

Worked example

A 16 by 12 foot room, planks covering 20 square feet per box, 7 inch planks, a 1/4 inch expansion gap each side, and 10% waste. Area is 192 square feet; with waste, 211.2; divided by 20 gives 10.56, so 11 boxes. Underlayment at 100 square feet per roll: 192 ÷ 100 = 1.92, so 2 rolls. Rows: the usable width is 144 − 0.5 = 143.5 inches, and 143.5 ÷ 7 = 20.5, so 20 full rows with 3.5 inches left for the twenty-first — a comfortable final row needing no adjustment.

Common mistakes

Skipping the expansion gap. A floating floor expands and contracts with humidity, and one fitted tight to the walls has nowhere to go but up — the buckling that follows is not repairable by trimming afterwards. Second, buying underlayment as an afterthought and discovering the roll does not reach. Third, laying out from one wall without checking the final row: ending on a half-inch sliver is both fragile and immediately visible, and it is trivially avoided by trimming the first row instead. Fourth, assuming every box covers the same area — it varies by product, so read the box rather than reusing a number from last time.

Common questions

Why does laminate need an expansion gap?

Because a floating floor is not fixed down; it expands and contracts with humidity as a single sheet. Without a gap at the perimeter it has nowhere to expand into and lifts in the middle.

What if the last row comes out very narrow?

Trim the first row so the difference is split between both walls. A one-inch sliver at one edge is fragile and obvious; two rows of a few inches each look deliberate.