For L-shaped rooms, split the floor into rectangles and put the smaller ones in "Extra area".
How the flooring calculator works
FlooringCalc multiplies the room's length by its width and adds any extra area for the square footage. It then adds a waste allowance for cuts that depends on the layout, divides by the coverage per box and rounds up, because flooring is sold only in whole boxes. The plank count divides the same area by the face area of one plank. Rows are laid along the longer wall, so the number of rows is the shorter dimension, minus a 3/8 in expansion gap at each wall, divided by the plank width. If the last row would be narrower than a third of a plank, the first and last rows are ripped to equal widths instead. Underlayment is the room area plus 5% for overlaps in 100 sq ft rolls, and trim follows the perimeter in 8 ft pieces.
Waste by layout
| Layout | Waste added | 180 sq ft room needs |
|---|---|---|
| Straight | 10% | 198 sq ft |
| Diagonal | 15% | 207 sq ft |
| Herringbone | 20% | 216 sq ft |
Rooms with many corners, closets or angled walls waste more than these figures, and so do long planks in short rooms. Trim counts do not subtract door openings. Follow the manufacturer's instructions for expansion gaps, acclimation and underlayment. Results are estimates for planning.
Frequently asked questions
How do I calculate how much flooring I need?
Multiply length by width for the square feet, add 10% for a straight layout (15% diagonal, 20% herringbone), then divide by the coverage per box and round up. A 15 × 12 ft room needs 198 sq ft, or 10 boxes of 20 sq ft.
How much extra flooring should I buy?
About 10% for a straight lay in a simple room, more for diagonal or herringbone patterns, many corners or a first-time installer. Keep a spare box for future repairs.
How big an expansion gap does floating floor need?
Commonly 1/4 to 1/2 in at every wall and fixed object; 3/8 in is a typical laminate figure. Check the manufacturer's instructions.
Is FlooringCalc free?
Yes, with no sign-up or ads.
Are my numbers saved?
Yes, in this browser only.