Enter your Roof Length, Roof Width, and Roof Pitch, then set your Roll Width, Roll Length, Side/End Overlap, and Waste Factor to find how many Rolls Needed — plus your Total Roof Area, Coverage per Roll, and Area with Waste so you can shop with confidence.
Rolls Needed
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Total Roof Area
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Coverage per Roll
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Area with Waste
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Calculate the base area (length × width) and adjust for roof pitch. Higher pitch roofs have more actual surface area than their base footprint.
Standard practice is 4-6 inches of side overlap and 6 inches of end overlap. Check your local building codes as requirements may vary.
Include 10-15% waste factor to account for cuts around roof features, mistakes, and material defects. Complex roofs may need higher waste factors.
Yes, steeper roof pitches have more actual surface area than the base footprint. A 6/12 pitch roof has about 18% more area than its base dimensions.
Most synthetic underlayment comes in 3-foot or 4-foot wide rolls. Traditional felt underlayment is typically 3 feet wide.
Roll lengths vary by manufacturer and type. Synthetic underlayment typically comes in 250-foot rolls, while felt may be 144 or 216 feet.