How to use
Enter the room length and width, the waste allowance and the coverage per box — it’s printed on the carton, usually 18–25 sq ft. You’ll see the floor area, the area including waste and how many boxes to buy. The same math works for laminate, vinyl plank (LVP) and engineered wood.
Waste depends on the layout: 5–7% is usually enough for straight, 10–15% for diagonal — it’s filled in when you choose. The calculator also works out the baseboard: room perimeter minus door openings, and how many pieces of the chosen length to buy.
How it’s calculated
Floor area × (1 + waste) ÷ coverage per box, rounded up to whole boxes.
How much waste to allow
- 5–7% for a straight lay in a simple rectangular room.
- 10–15% for diagonal installs and rooms with lots of corners, closets and pipes.
- Herringbone and wide or long planks: up to 15–20% — follow the manufacturer’s guidance.
Examples
- A 16 × 13 ft room, 7% waste, 20 sq ft per box: 208 sq ft of floor, 222.6 sq ft with waste, so 12 boxes (240 sq ft).
- The same room laid diagonally with 15% waste: 239.2 sq ft — still 12 boxes.
- A 12 × 11 ft bedroom, 10% waste, 22.5 sq ft boxes: 145.2 sq ft, 7 boxes.
FAQ
Do I need to account for the expansion gap? No — the 1/4–3/8 in gap at the walls is hidden by baseboard or quarter round and doesn’t change the amount.
How do I measure an L-shaped room? Split it into rectangles, add up their areas and enter, for example, length = total area and width = 1.
Is underlayment calculated the same way? Yes, by floor area, but with less waste because it’s laid edge to edge.
For tile, the tile calculator also works out grout and thinset.