Work out how many boxes of laminate, vinyl or hardwood flooring you need from the room area and the coverage per box.
Coverage per box is printed on the packaging (around 2 to 2.5 m² is common for laminate). A 10 percent waste allowance covers cuts and the offcuts you cannot reuse; increase it for diagonal layouts or busy room shapes.
Find the room area (length times width), add a waste allowance, then divide by the coverage printed on each box and round up. This tool does it and also shows the total area the boxes will cover.
Boards are cut to fit at walls and around obstacles, and the offcuts often cannot be reused. Around 10 percent extra is standard, rising to 15 percent or more for diagonal patterns or rooms with lots of corners.
It is wise to keep one spare box from the same batch. If a board is damaged later, a batch match avoids visible colour or texture differences across the floor.