Packs are the easy part. What ruins a laminate floor is finding halfway across that the last row is a one-inch strip — so this checks the row layout, and works out the underlayment while it is at it.
Boxes are simple arithmetic. The part that catches people out is the row layout, and it only becomes obvious when you are three quarters of the way across the room.
Divide the room width by the plank width and you rarely get a whole number. Whatever is left over becomes the final row, and if that remainder works out at an inch or two you have a problem: a sliver that thin is fragile, hard to click into the row before it, and looks like a mistake.
The fix is to rip the first row narrower so the first and last rows come out roughly the same width. Doing that costs you nothing if you plan it before you start, and costs you a row of flooring if you notice at the end. The row check above tells you which situation you are in.
Laminate is a photographic layer over a high-density fibreboard core, and that core is wood. Water that gets past a seam swells it, and swelling is permanent — the plank never goes back down. That is why laminate belongs in bedrooms, hallways and living rooms rather than bathrooms.
If the room is one where a washing machine could leak or a shower could overflow, vinyl plank is the safer material. It costs about the same and does not care about water.
A floating laminate floor needs a foam or felt layer under it. It absorbs the hollow click of the boards, evens out small imperfections in the subfloor, and on concrete it carries the moisture barrier.
Underlayment is sold by the roll in square feet, and you need the plain floor area — no waste factor, because it is trimmed and butted rather than cut around. The ticket gives you that figure separately.
Laminate expands and contracts across its width with humidity. A floating floor fitted tight to the walls has nowhere to go and lifts in the middle instead, usually in the first damp summer.
Leave about a quarter inch around the whole perimeter, including around pipes and door frames, and cover it with skirting or beading. The gap does not change how much flooring you order — the planks still run wall to wall — but forgetting it costs you the floor.
| Assumption | Value used |
|---|---|
| Waste — straight run | 10% |
| Waste — diagonal | 15% |
| Waste — herringbone | 20% |
| Default pack coverage | 20 ft² |
| Minimum sensible last row | 2 in |
| Expansion gap | 0.25 in |
| Underlayment | plain floor area, no waste |
| Packs rounded up to whole packs | yes |
Pack coverage is the number to check — it varies from about 15 to 26 ft² between brands, and the calculator is only as right as that figure.