Worked example: flooring for a 12 × 14 ft bedroom
Hypothetical educational example. Straight layout uses this calculator’s 7% default, not 10%. Twenty square feet per box is a scenario assumption. One spare carton is an extra unopened box for later repairs, kept separate from install waste.
Inputs
| Room | 12 × 14 ft, no L-shape |
|---|---|
| Layout | straight |
| Waste | blank, so 7% |
| Coverage | 20 sq ft per box (scenario) |
| Spare cartons | 1 |
Arithmetic
- Area = 168 sq ft.
- Install waste = 168 × 0.07 = 11.76 sq ft, displayed as 11.8 sq ft. Area used for packing = 179.8 sq ft.
- 179.76 ÷ 20 = 8.988, which rounds up to 9 boxes for installation.
- Boxes to buy = 9 + 1 spare = 10 boxes = 200 sq ft.
Required, waste and purchase
- Required
- 9 boxes to install, covering the 7% allowance and a fraction of a box of pack roundup (about 0.2 sq ft).
- Purchased
- 10 boxes, because the example keeps one spare carton. The underlayment line on the calculator is 176.4 sq ft (area × 1.05). That is an area, not a roll count. Baseboard length shown is the 52 ft perimeter and does not subtract a door.
- Units
- US feet and square feet per carton.
Assumptions
- 7% is this tool’s straight-layout default. The same tool’s table also mentions 5–7% for a simple rectangle. The example does not switch to 5%.
- 20 sq ft per box is not a verified carton. Laminate boxes are a different calculator.
What this example does not decide
- Not a subfloor moisture specification.
- The 1.05 underlayment factor is an editorial area allowance on the flooring calculator, not a roll yield.
Where to go next
- Flooring calculator — Run these inputs
- Flooring topic — Box method
- How to measure a room — Measuring steps
- Baseboard calculator — Trim after the door deduction you actually have
- Laminate calculator — Use this instead if the product is laminate
Questions
Why is install waste 7% and not 10%?
The waste field is blank, so the straight-layout default on this calculator applies. That default is 7%. Typing 10 would be a different order.
Is the tenth box waste?
No. Nine boxes are the install quantity, including 7% and the last-carton roundup. The tenth box is the spare carton this scenario chose to keep.
Sources
- Flooring calculator layout defaults on this site — accessed 2026-11-09: “Straight default on this tool is 7%.”