The formula
packs = area × (1 + allowance) ÷ m² per pack, rounded up
Where it comes from
The sum is simple and the allowance is the only part open to argument. In a rectangular room with the boards running parallel to the long wall you lose around 5 %: the offcut at the end of one row starts the next. If the floor runs diagonally, if the room has awkward corners, or if the board is very long, that figure climbs to 12 or 15 % with no effort at all. That is why the allowance is a field on the form and not a constant.
How to work it out by hand
- Measure the area of the room
- Add the cutting allowance according to how the boards run
- Divide by the square metres each pack contains
- Round up: half a pack is not sold
What is worth knowing
Three things that stay out of the sum and turn up on the invoice. Underlay goes below and is bought for the clean area, with no allowance, because it overlaps and trims with no real waste. The perimeter expansion gap — 8 to 10 mm against every wall — is not optional: laminate expands with humidity and without that gap it ends up lifting in the middle of the room. And transition profiles between rooms and under doors are counted in pieces, not metres. Always keep half a pack: in a few years that model will be gone, and one damaged board means lifting half a room.