Construction Calculators

Underlayment Calculator

Calculate underlayment area, waste, roll quantity, purchased coverage, and cost.

Last updated July 23, 2026
Underlayment roll estimator

Floor dimensions and package coverage

Underlayment to cover
Measured area
Full rolls
Purchased coverage
Extra purchased
Coverage per roll
Estimated cost
Results are estimates for informational purposes. Verify critical calculations and project requirements independently.

How Much Underlayment Do You Need?

Underlayment normally covers the same floor area as the installed flooring, plus overlap and cutting allowance. Enter the coverage supplied by one roll or package.

Verify Compatibility

Confirm the flooring manufacturer permits the selected underlayment and check requirements for vapor barriers, seams, thickness, and subfloor type.

Calculation Standards

This tool uses documented formulas and high-precision internal values. Displayed results may be rounded for readability. Review the assumptions and verify important decisions with a qualified professional.

Read our calculation methodology