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Roofing Underlayment Rolls Calculator

Rolls of synthetic underlayment for a roof.

Compute the number of rolls of synthetic roofing underlayment needed for a roof, including 10 % overlap and waste, given the roof area in squares (1 sq = 100 ft²).

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

sq

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Rolls = ceil(squares · 100 · 1.10 / coverage_ft2_per_roll).

In depth

Compute the number of rolls of synthetic roofing underlayment needed for a roof, including 10 % overlap and waste, given the roof area in squares (1 sq = 100 ft²).