How to use the flooring calculator
- Measure each room wall to wall. Go to the bottom of the baseboard and round up to the next inch. For L-shaped or odd-shaped rooms, split the floor into rectangles and add each one as its own room.
- Add closets and nooks as extra square feet.
- Enter the coverage per box from the carton. Vinyl plank and laminate boxes usually hold about 18–24 sq ft.
- Choose a waste allowance. 7% for a simple rectangular room, 10% as a standard, 15% for diagonal layouts or rooms with many doorways and angles.
- Turn on stairs if you’re continuing the floor up a staircase. Treads, optional risers and stair nose moldings are added separately with their own higher waste factor.
Flooring formula: square feet to boxes
With waste = floor area × (1 + waste %)
Stairs = steps × stair width × (tread depth + riser height) ÷ 144 × 1.20
Boxes = (floor with waste + stairs) ÷ sq ft per box → round up
Stairs get a separate 20% allowance because every tread and riser is cut individually and offcuts are rarely long enough to reuse. Stair nose molding is usually sold in 94 in lengths, so one piece covers two standard 36 in steps.
Worked example: two rooms, a closet and a staircase
- Living room 14 × 12 ft = 168 sq ft
- Bedroom 11 × 10 ft = 110 sq ft
- Closet = 12 sq ft
Floor total 290 sq ft; with 10% waste, 319 sq ft. Thirteen 36 in wide stairs with 11 in treads and 7.5 in risers add 13 × 36 × 18.5 ÷ 144 = 60.1 sq ft, or 72.2 sq ft with 20% waste. Total 391 sq ft. With 23.6 sq ft per box that’s 16.6, so buy 17 boxes — and 7 stair nose pieces.
Always round up to a whole box and keep one unopened box. Matching a discontinued color or dye lot years later is nearly impossible.
Waste factor and buying tips
- Check the lot number. Buy all boxes from the same production lot so color and texture match.
- Acclimate the flooring in the room for the time the manufacturer specifies — often 24–48 hours — especially laminate and wood-based products.
- Underlayment is separate. Many LVP products have it attached; if not, buy underlayment for the floor area without the waste factor (it’s rolled out in big pieces).
- Plan transitions. Count doorways where the new floor meets carpet, tile or another floor height and buy a transition strip for each.
- Expansion gaps (about ¼ in at the walls for most floating floors) are covered by baseboard or quarter round; measure the room perimeter if you need new trim.
- Long hallways and open plans may need a transition joint per the maker’s maximum run length — check the install guide.
Doing a bathroom or kitchen in tile instead? Use the tile calculator. Hanging new walls first? The drywall calculator covers sheets, mud and tape.
Waste allowance by layout
| Layout | Suggested waste |
|---|---|
| Simple rectangular room, straight lay | 5–7% |
| Typical room with a closet and doorways | 10% |
| Diagonal lay or many angles | 15% |
| Herringbone / chevron | 15–20% |
| Stairs | 15–20% |
Sources & assumptions
How this calculator gets its numbers. Full method: our methodology.
- Floor area is length × width per room; stairs are added tread by tread.
- Default waste is 10%. Makers commonly suggest about 5% for straight lay in simple rooms and 10–15% for diagonal layouts or many cuts.
- Boxes are rounded up to whole cartons, using the carton coverage you enter.
Sources
- Mullican Flooring (via Lowe's product documents), How to Calculate the Correct Footage When Purchasing Hardwood Flooring. Add about 5% for culling and cuts; 10–15% for diagonal installs.
Last reviewed . Product figures vary by brand; the label on what you buy wins.
Frequently asked questions
How do I calculate how much vinyl plank flooring I need?
Multiply each room's length by its width, add them up, add 10 percent for waste, and divide by the square feet in one box. Round up to a whole box. A 12 × 15 ft room is 180 sq ft, or 198 sq ft with waste, which is 10 boxes at 20 sq ft per box.
How much flooring do I need for stairs?
For each step, multiply the stair width by the tread depth plus the riser height. A 36-inch stair with 11-inch treads and 7.5-inch risers uses about 4.6 sq ft per step, so 13 steps need about 60 sq ft before waste. Add 15 to 20 percent because each piece is cut individually.
How much extra flooring should I buy?
Ten percent is a good default. Use 5 to 7 percent for a simple rectangle and 15 percent or more for diagonal layouts, herringbone or rooms with many angles. Keep a spare box for repairs.
How do I measure an odd-shaped room for flooring?
Divide the room into rectangles, measure each one and add them as separate rooms in the calculator. For a small angled section, measure the rectangle that encloses it; the extra is covered by your waste allowance.
How many stair nose pieces do I need?
One per step if your stairs are wider than half a molding length. Most stair nose moldings are 94 inches long, so one piece covers two standard 36-inch steps; 13 steps need 7 pieces.