Key takeaways
- Flooring is sold by the box, and each box covers a fixed number of square feet.
- Boxes = room area × (1 + waste%) ÷ box coverage, always rounded up.
- Waste runs from 5% for a straight layout to 15–20% for herringbone or angled rooms.
- Buy from one dye lot and keep one spare box for repairs.
How to estimate flooring
Flooring is sold by the box, and each box covers a fixed number of square feet. To size an order, find the room's area, add a waste allowance for cuts and the odd damaged plank, then divide by the coverage printed on the box. Because you can only buy whole boxes, the result is always rounded up.
The coverage figure comes straight off the product label or listing — it varies by plank size and is usually somewhere between 18 and 24 square feet per box.
Worked example: a 12 × 15 ft room
For a 12 ft × 15 ft room with 20 sq ft boxes and a 10% waste allowance: 12 × 15 = 180 square feet. Adding 10% waste gives 180 × 1.10 = 198 square feet. Dividing by the box coverage, 198 ÷ 20 = 9.9, which rounds up to 10 boxes — and those 10 boxes cover 200 square feet, leaving a little for repairs.
Waste allowance by layout
| Layout | Waste allowance |
|---|---|
| Straight / grid | 5% |
| Diagonal | 10% |
| Herringbone / chevron | 15% |
| Lots of cuts or angled rooms | 15–20% |
Buying tips
Always buy from the same dye lot, since flooring color can shift between production runs and a box bought months later may not match. Keep one spare box for future repairs rather than returning it. If you're laying square tile instead of plank, size it with the tile calculator, which works in tiles per box the same way.
Frequently asked questions
How many boxes of flooring do I need?
Room area × (1 + waste%) ÷ sq ft per box, rounded up. A 12 × 15 room at 10% waste with 20 sq ft boxes needs 10 boxes.
How much waste should I add?
5% for a straight or grid layout, 10% diagonal, 15% for herringbone or chevron, and 15–20% for rooms with lots of cuts or angled walls.
How many boxes for a 20×20 room?
400 sq ft × 1.10 = 440 sq ft; at 20 sq ft per box that's 22 boxes.
How do I read the square feet per box?
It's printed on the box label or product page — commonly 18 to 24 sq ft for laminate and vinyl plank.
Should I buy an extra box?
Yes — buy from one dye lot and keep a spare box for repairs, because color shifts between production runs.
Do I round boxes up or down?
Always up. Flooring is sold by the box, so 9.9 boxes means buying 10; the leftover covers mistakes and damage.
Flooring makers recommend a 5–10% waste allowance for most layouts — Shaw Floors publishes installation guidance along these lines. Always buy from a single dye lot and keep one spare box for repairs.
Last reviewed June 2026