Room sizes in, boxes out — with the right waste allowance for your layout, underlayment, transition strips and a priced total.
Rooms
Add a row per room. Leave unused rows blank. For an L-shaped room, split it into two rectangles.
The flooring
Printed on the carton. Laminate boxes are usually 18–24 ft², engineered wood 20–30 ft², vinyl plank 24–36 ft².
%
Trim and underlay
Boxes to buy
—
Floor area—
Area with waste—
Area in square metres—
Coverage you will actually buy—
Spare left over—
Underlayment rolls—
Baseboard or quarter round—
Estimated flooring cost—
—
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Buy by the box, not by the square foot
Flooring is priced per square foot but sold in whole cartons, so the real order is area × (1 + waste) ÷ coverage per box, rounded up. A 192 ft² room with 10% waste needs 211.2 ft², which at 20.15 ft² a box is 10.5 boxes — so eleven. That final round-up is not optional and it is why the square footage price never quite matches the till total.
Waste is set by the layout, not by your care
Situation
Allowance
Simple rectangle, straight lay
7%
Normal room with doorways and obstacles
10%
Several rooms, hallways, angled walls
15%
Diagonal lay
20%
Herringbone or chevron
25% or more
Long planks waste more than short ones, because the offcut at the end of a run is more likely to be too short to start the next. Wide plank and long-format flooring sits at the higher end of each band.
Underlayment and expansion gaps
Floating floors — laminate and most vinyl plank — need underlayment for cushioning, sound and moisture. Some products come with it pre-attached, in which case you skip it entirely. Over concrete, add a 6 mil vapour barrier underneath regardless of what the underlayment claims.
Every floating floor also needs an expansion gap of about ¼ to ⅜ inch around the entire perimeter and against every fixed object. Wood and laminate move with humidity, and a floor pinned tight at the walls will buckle in the middle of the room in its first humid summer. The gap disappears under the baseboard.
Leave the cartons flat in the room where they will be installed for 48 to 72 hours before you start. The planks take up the room's temperature and humidity, and installing them straight off a cold truck is how gaps appear a fortnight later. While laying, pull planks from three or four boxes at a time — batch colour varies slightly, and drawing from one box at a time can leave a visible band across the floor.
Order it all at once
Dye lots differ between production runs, and a top-up box bought two months later will rarely be an exact match. Order the full amount in one go, and keep whatever is left over: a spare box in the garage is the only practical way to repair a damaged plank years afterwards, since the product line will almost certainly have been discontinued.
Direction and thresholds
Running planks parallel to the longest wall, or toward the main light source, makes a room look larger and hides the seams. Every doorway between rooms and every change of surface needs a transition strip, and any run over about 40 ft in one direction generally needs an expansion joint too — check what the manufacturer's warranty requires, because ignoring it usually voids it.
Multiply the floor area by one plus your waste allowance, then divide by the coverage printed on the box and round up. A 200 ft² room at 10% waste needs 220 ft², which is 11 boxes at 20 ft² each.
How much extra flooring should I order?
Ten percent for a normal room, 15% across several rooms or with angled walls, and 20 to 25% for diagonal, herringbone or chevron layouts. Order the extra with the main batch so the dye lot matches.
Do I need underlayment under laminate?
Yes, unless the planks come with it pre-attached. It cushions, quietens and helps with minor subfloor irregularities. Over concrete you also need a separate vapour barrier, whatever the underlayment claims to include.
How big should the expansion gap be?
About ¼ to ⅜ inch around the whole perimeter and against every fixed object — door frames, pipes, cabinets. The baseboard or quarter round covers it. Without the gap the floor has nowhere to expand and will buckle.
Should I buy flooring by the box or by the square foot?
Prices are quoted per square foot but stock is sold in whole boxes, so you always pay for the rounded-up number of boxes. That is what this calculator gives you, along with how much spare you will be left holding.