How it works
Measure the room's length and width wall to wall, add any closets or alcoves, and the calculator adds a waste factor and tells you how many boxes to buy based on the coverage printed on the carton.
A 10% allowance covers end cuts, damaged pieces and fitting around door frames for a straight lay. Use 15% for diagonal, herringbone or rooms with lots of angles. Keep an unopened box for future repairs; dye lots change.
Underlayment is usually sold by the roll in 100 or 200 sq ft; buy enough for the room area without waste.
Formula
Flooring = (length × width + extra area) × (1 + waste). Boxes = flooring ÷ coverage per box, rounded up.
Questions people ask
How much extra flooring should I buy?
Ten percent for a standard straight installation, 15% for diagonal or patterned layouts, and up to 20% for herringbone or very irregular rooms.
Do I measure under cabinets and appliances?
Not under fixed cabinets or islands; floating floors should not go under cabinets. Do include spaces under movable appliances like a range or refrigerator if the floor runs there.
How do I measure an L-shaped room?
Split it into two rectangles, find each area and add them together. The square footage calculator handles L-shapes directly.