How the flooring calculator works
The calculator multiplies room length by room width, adds your selected waste allowance, then rounds the number of boxes up so you do not end up short.
How much waste should you add?
| Project | Planning allowance |
|---|---|
| Simple rectangular room | 5–10% |
| Many cuts or angled walls | 10–15% |
| Pattern matching / complex layout | 15% or more may be appropriate |
Formula
Purchase area = room area × (1 + waste percentage). Boxes needed are purchase area divided by the box coverage, rounded up to the next whole box.
Worked example
An 18 × 12 foot room is 216 square feet. Adding 10% waste gives a target of 237.6 square feet. If each box covers 23.8 square feet, the project requires 10 boxes covering 238 square feet.
Before ordering
- Use the coverage printed on the exact product package.
- Measure closets and connected spaces you plan to cover.
- Consider keeping unopened extra material for future repairs.
Assumptions and limitations
The calculator models one rectangular area and rounds to whole boxes. It excludes closets, transitions, pattern direction, and unusable offcuts unless they are included in the measurements or waste allowance.
Frequently asked questions
How much extra flooring should I buy?
Five to 10% often suits a simple room. Diagonal layouts, patterns, and spaces with many cuts may need 10–15% or more.
Why is actual box coverage higher than the target?
Flooring is sold in whole boxes, so the package count rounds up rather than leaving the project short.