Estimate how much underlayment to order from roof area and roll coverage, then combine your material price with an editable labor allowance. The calculator also shows a broad 2026 installed benchmark.
Use the benchmark to screen a budget. For purchasing, use the exact coverage printed on the product and the installation requirements for your roof system.
Enter roof surface area, the product’s effective roll coverage, your roll price and a labor rate from a quote or planning assumption.
Underlayment sits between the roof deck and the finished roof covering. In 2026, Angi publishes a broad replacement range of about $0.60–$2.70 per square foot in most cases. That range includes projects with different product types, roof pitches and local labor markets, so the calculator lets you replace generic assumptions with your own roll price and labor rate.
Use roof surface area × overlap/waste allowance ÷ effective roll coverage, then round up to whole rolls. Do not use advertised nominal coverage if the product’s required side laps and end laps reduce effective coverage.
| Category | Why the cost can differ |
|---|---|
| Asphalt-saturated felt | Lower material cost, heavier rolls and product-specific coverage. |
| Synthetic underlayment | Often larger coverage per roll and different fastening / exposure requirements. |
| Self-adhered leak barrier | Higher material cost and typically used in specified zones or systems rather than priced like field underlayment. |
Valleys, eaves, penetrations and other vulnerable locations may require a different membrane or detail. Ask the roofer to identify the main field underlayment and any separate leak-barrier material so two quotes can be compared on equal scope.
The 2026 benchmark is based on Angi’s roof underlayment replacement cost guide. HomeGuide also publishes broader installed underlayment ranges in its roofing material pricing guide.
Angi publishes a broad 2026 replacement range around $0.60 to $2.70 per square foot in most cases. Product type, roof pitch, local labor and whether the work is part of a full reroof can change the final price.
It depends on effective coverage per roll and required overlap. For example, 2,000 sq ft with a 10% allowance is 2,200 sq ft. At 1,000 effective sq ft per roll, you would round up to 3 rolls.
Material pricing often differs, but total installed cost also depends on roll coverage, fastening, labor and the roof system. Compare the exact products rather than material names alone.
Many full replacement proposals include new underlayment, but the product and detail zones can differ. Ask for the exact product and scope in writing.
Allow for required laps, cuts and detail areas. The correct allowance depends on the product instructions and roof geometry, so use the manufacturer’s effective coverage when possible.