Underlayment planning
Underlayment calculator for effective coverage
Estimate underlayment from manufacturer-declared effective installed coverage.
Underlayment planning
Result
How to estimate underlayment
Treat underlayment as a separate layer. Package coverage must be the effective installed area after the product's required overlaps, not simply roll width times length.
How to use it
- Enter the floor area to cover and any additional waste you choose; do not count required overlap twice.
- For a package estimate, enter the selected underlayment's manufacturer-declared effective installed coverage per package.
Formula
Required underlayment area = floor area × (1 + additional waste ÷ 100). With several confirmed compatible effective-coverage sizes, the calculator chooses whole packages with the least area remainder.
Example
For 20 m² of floor, 10% additional waste and 5.5 m² effective installed coverage per pack, required underlayment is 22 m². Buy 4 packs; the area remainder is 0 m².
What the estimate uses
- You supply effective coverage for one selected compatible product system and an additional waste allowance; no overlap width is inferred.
Limits
- Nominal roll width × length is not substituted for effective installed coverage and overlap is not calculated from roll geometry.
- This does not check acoustic, moisture, substrate, floor-product compatibility, layout, prices or stock.
Underlayment question
Why use effective coverage instead of roll dimensions?
Required overlaps and seams can reduce the area a package actually covers. Use the effective installed coverage stated for your product and installation method.