How the calculator works
For boxed flooring (vinyl plank, laminate, hardwood and tile) it adds up the floor area of every room, adds a waste allowance for cuts, divides by the square feet in one box, and rounds up because stores sell whole boxes. Then it adds any spare boxes you want to keep for repairs. The formula is: boxes = round up(floor area × (1 + waste %) ÷ sq ft per box) + spares.
Carpet is different. It comes off a roll of fixed width, so the calculator lays full-width strips across each room in whichever direction uses less carpet, adds a small trimming allowance to each strip, and converts the total to square yards (square feet ÷ 9).
How much waste to allow
| Layout | Default | Where it comes from |
|---|---|---|
| Straight, parallel to a wall | 7% | Mullican Flooring: about 5–7% for a standard hardwood install |
| Diagonal (45°) | 15% | Mullican Flooring: 10–15% for a diagonal install, because angled cuts are larger |
| Herringbone or other pattern | 15% | Midpoint of the 10–20% one herringbone vinyl plank guide (Wickes) recommends; more for small rooms |
Mullican says to allow more for character or builder grades, where you may cull boards you don't like, and the herringbone guide says smaller areas need a larger waste factor. Mullican also recommends buying one or two extra cartons to keep for repairs after leaks or damage, since a later batch may not match.
Worked example: LVP in three rooms
- Living room 16 × 13 ft = 208 sq ft. Bedroom 12 × 11 ft = 132 sq ft. Hallway entered as 30 sq ft. Total floor: 370 sq ft.
- Straight layout, 7% waste: 370 × 1.07 = 395.9 sq ft.
- Cartons hold 22 sq ft: 395.9 ÷ 22 = 17.99, rounded up to 18 boxes. Plus 1 spare = 19 boxes, or 418 sq ft.
- At $3.50 per sq ft: 418 × $3.50 = $1,463. Underlayment at 100 sq ft per roll: 4 rolls at $30 = $120. Total material: $1,583.
Switch the layout to diagonal and the waste jumps to 15%: 370 × 1.15 = 425.5 sq ft, or 20 boxes plus the spare. That is two extra boxes, about $154 more at these prices.
Carpet example
The 16 × 13 ft living room on a 12 ft roll: laying strips along the 16 ft side needs two strips (13 ft is wider than one 12 ft strip), each 16.5 ft long with trimming, for 396 sq ft. Running them along the 13 ft side also needs two strips but only 13.5 ft long, for 324 sq ft or 36 sq yd. The calculator picks the second. That is far more than the room's 208 sq ft, which is why roll width matters. This is a simple full-strip plan: an installer may fill a narrow gap with an offcut from another room, so a store's measure can come in lower.
Renovating an apartment?
Many co-op and condo buildings set rules for floor replacement, such as approval, contractor insurance or soundproofing, in their alteration agreement or house rules, so check before you buy. See renovating a co-op or condo. Getting a home ready to list? Use preparing your home for sale. Measure odd-shaped rooms with the square footage calculator, and budget other projects with the paint calculator.