Shops sell whole packs. The useful number is not “20 square metres” — it is how many cartons you walk out with after waste for cuts, and after the last pack that does not divide evenly.
Room and packs
Estimate
Packs to buy11
Net floor area
20 m²
Area with waste
22 m²
Area in those packs
23.672 m²
Leftover after laying
1.672 m²
Estimate only. Underlay, profiles, and door bars are extra. Buy every pack from the same lot. A bay window or a diagonal hallway can eat a pack on its own.
How the calculator works
Laminate and vinyl are sold by the pack. A pack has a printed coverage — often 1.76 m², 2.131 m², or 2.152 m² for a standard laminate carton. You cannot buy 0.4 of a pack, and the last board you cut for the doorway does not go back in the box for a refund.
The calculator takes the room (length × width, or a total area you already measured), adds a waste percentage that depends on how you will lay the boards, then divides by the pack coverage and rounds up. The headline is the number of cartons to put in the trolley.
Waste is not padding we invented. A straight lay in a rectangular room still loses the offcut at each end of a row; 8% is a lean allowance. Rooms with jogs, radiators, or a herringbone pattern eat closer to 10%. A diagonal lay throws more triangles in the corners — 12% is the usual shop advice. You can type any percentage if you already know the room is awkward.
Whole packs, leftover boards
On the worked example a 5 × 4 m room is 20 m². Ten percent waste makes 22 m². A 2.152 m² pack goes into 22 only 10.22 times, so you buy 11 packs — 23.672 m². The extra 1.672 m² is the remainder of the last carton, not a mistake.
Buy every pack from the same lot number. If the shop is one pack short, wait. Underlay, T-profiles, and door bars are a separate basket; this tool does not add them.
Worked example
The calculator above is pre-filled with this room so the numbers on the page match.
5 × 4 m, 10% waste, 2.152 m² pack
Net area = 5 × 4 = 20 m².
Area with waste = 20 × 1.10 = 22 m².
Packs = ceil(22 ÷ 2.152) = ceil(10.223) = 11.
Bought = 11 × 2.152 = 23.672 m².
Leftover after laying = 23.672 − 22 = 1.672 m².
Questions people ask before they order packs
How many packs of laminate do I need?
Multiply the room’s length by its width, add 8–12% for waste, divide by the coverage printed on the pack, and round up. A 5 × 4 m room with 10% waste and 2.152 m² packs needs 11 packs.
How much waste should I allow?
8% for a straight lay in a simple rectangle, 10% if the room has alcoves or you are laying a pattern, 12% for a diagonal. Stairs, a bay, or a hallway of closets can justify more — type it.
Should I measure in metres or square metres?
Either. Length and width are easier to check with a tape. If you already have a floor-plan area, type it in the area field and it overrides the rectangle.
Does this include underlay and profiles?
No. Underlay is usually sold by the roll to the same area (often without the same waste). Profiles and door bars are counted by the doorway, not by the metre of floor.
Can I return an unopened pack?
Often yes, if the shop still stocks that lot — but do not plan on it. The leftover from the last opened pack is yours. Keep one spare sealed pack if the floor is a special order.