How it works
The formula
boxes = area × (1 + waste) ÷ sq ft per box, rounded up
cost = price per sq ft × boxes × sq ft per box
underlayment rolls = area ÷ 100, rounded up
Assumptions
- Waste covers cuts at walls and bad boards. Straight layouts get 10, diagonal and herringbone get 15. Installers often quote 5 to 10 percent for straight and 10 to 15 for diagonal; we use the top of each so you do not come up short.
- Box coverage varies by brand. We start at 20 sq ft for laminate, 24 for vinyl plank and 20 for hardwood, which are typical but not a rule. Read the number on the box and type it in.
- Flooring is priced per sq ft but only sold in full boxes, so the cost is price × boxes × sq ft per box. That is slightly more than price × area, and it is what the register charges.
- Underlayment comes in 100 sq ft rolls and covers the floor area without waste. It starts on for laminate and hardwood and off for vinyl plank, because many vinyl planks have a pad attached. Check yours.
- Baseboard and transition strips are shown as feet around the walls, not priced. Subtract doorways yourself and add a few feet for cuts.
- Metric: type meters and m² per box. The sizes convert to feet for the math, and prices stay per sq ft.
Worked example
A 12 × 14 ft room, straight laminate, 20 sq ft boxes
- Area: 12 × 14 = 168 sq ft
- Add 10% waste: 168 × 1.1 = 184.8 sq ft
- Boxes: 184.8 ÷ 20 = 9.24, so buy 10 boxes (200 sq ft)
- Underlayment: 168 ÷ 100 = 1.68, so 2 rolls
- At typical prices, the flooring and underlayment together come to $260–$900
Common room sizes
| Room | Sq ft | With 10% | Boxes |
|---|---|---|---|
| 10 × 10 ft | 100 | 110 | 6 |
| 12 × 12 ft | 144 | 158.4 | 8 |
| 12 × 14 ft | 168 | 184.8 | 10 |
| 15 × 20 ft | 300 | 330 | 17 |
| 20 × 20 ft | 400 | 440 | 22 |
Straight layout, 10% waste, 20 sq ft per box. Your boxes may hold more or less, so check the box.
Questions people ask
How much flooring do I need for a 12x12 room?
A 12 × 12 room is 144 sq ft. With 10% waste that is 158.4 sq ft, or 8 boxes of 20 sq ft. For a diagonal layout (15%) it is 9 boxes.
How much extra flooring should I buy?
10% for a straight layout and 15% for diagonal or herringbone. For the 12 × 12 room, no extra at all would be 8 boxes, against 8 with waste. Rooms with many corners, doorways or closets can waste more. Keep the leftover boxes for repairs, since the same dye lot may not be sold later.
What is the box coverage?
It is printed on the box, in sq ft per box. Typical starting points are about 20 sq ft for laminate, 24 for vinyl plank and 20 for hardwood, but brands differ. Type your box's number into the calculator, because the box count depends on it.
Do I need underlayment?
Usually for laminate and hardwood, depending on the product and subfloor. Many vinyl planks come with a pad attached, so you can skip it. Check the manufacturer's instructions, since adding a second pad can void the warranty. A 144 sq ft room needs 2 rolls of 100 sq ft.
Should I acclimate the flooring?
Most manufacturers say yes. Leave the unopened boxes in the room, at normal living temperature, before you install. Laminate and vinyl plank are often given 48 hours and hardwood can need several days, but the instructions in the box rule. It helps the boards settle to the room's humidity and avoids gaps and buckling later.