How the flooring underlayment calculator works
Net floor area = length × width − excluded area. Adjusted area = net area × (1 + allowance ÷ 100). Full rolls = ceiling(adjusted area ÷ printed coverage per roll).
Worked example
A 14 × 12 ft room is 168 sq ft. With 5% additional allowance, 176.4 sq ft requires two rolls covering 100 sq ft each.
Before you order
Some flooring products have attached padding or require specific vapor barriers. Follow flooring and underlayment manufacturer compatibility and installation guidance.
All results are planning estimates, not a guarantee of installed material quantity or a quote. Measure the actual project, verify product labels, and follow the manufacturer’s instructions.
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