Area, plus waste, divided by box coverage
The whole estimate is three steps. Measure the floor, pad it for waste, then split that across boxes and round up.
A 12 × 15 ft room is 180 sq ft. At 10% waste that is 198 sq ft. If each box covers 20 sq ft, 198 ÷ 20 = 9.9, which rounds up to 10 boxes. The rounding matters — ignore it and you finish one plank short.
Waste depends on the layout, not just the material
| Material | Straight room | Irregular / L-shape | Diagonal / herringbone |
|---|---|---|---|
| Ceramic tile | 5–10% | 15–20% | 20–25% |
| Hardwood | 10% | 15% | 15–20% |
| Laminate | 5–10% | 10–15% | 15–20% |
| Vinyl / LVP | 8–10% | 12–15% | 15–20% |
| Carpet | 10% | 15% | 20% |
Diagonal and herringbone patterns cut every plank at 45°, and the offcut is a triangle you usually cannot reuse — which is why the waste allowance jumps.
Box coverage varies a lot — check the label
- Laminate — roughly 20 sq ft per box, but ranges from 15 to 36.
- Hardwood — usually 20 to 25 sq ft.
- Vinyl / LVP — commonly 30 sq ft, spanning 20 to 40.
- Tile — anywhere from 5 to 50 sq ft depending on tile size.
- Odd rooms — split an L-shape or an alcove into rectangles, measure each, add the areas, then apply waste to the total.
Common questions
How much extra flooring should I buy?
Add 10% waste for a plain rectangular room, 15% for an L-shape or lots of cuts, and 20 to 25% for a diagonal or herringbone layout. The extra covers cuts, mistakes and a few boards kept for future repairs.
How many boxes of flooring do I need?
Divide the total area including waste by the square footage one box covers, then round up to the next whole box. A box never comes in halves, so 21 sq ft of material at 20 sq ft per box is two boxes.
Why round up instead of buying the exact amount?
You cannot buy part of a box, and dye lots vary between production runs. Ordering the extra now means the leftover matches; buying more later often will not.
