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Ridge Vent Calculator

Attic Floor (sq ft)

Ridge Length (ft)

Roof Pitch

Waste Factor

Result

—lin ft

◆ LIVE 3D PREVIEW

NFA Required

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Soffit Vent

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How to Calculate Ridge Vent

Use this free ridge vent calculator to get instant, accurate results for your construction project. Simply enter your measurements above and the calculator will automatically compute the result using industry-standard formulas.

Pro Tip: Always add 10-15% extra material to account for waste, cuts, and job-site conditions. This is standard practice recommended by experienced contractors.

Related Calculators

▸ Ice Dam Prevention ▸ Roof Vent ▸ 2x4 ▸ 3 4 5 Rule ▸ Ac Size ▸ Ac Tonnage

💡 Pro Tips — Ridge Vent

3 bundles = 1 square (100 sqft) for standard asphalt shingles.
Pitch multiplier matters: A 6/12 pitch roof uses 12% more material than a flat roof.
Always install ice & water shield on the first 24" from the eave in cold climates.
Ventilation: 1 sqft of net free vent area per 150 sqft of attic floor space.
Metal roofing lasts 50+ years vs 20-30 for shingles — better long-term ROI.

📊 Pitch Multiplier Table

Pitch	Multiplier	Extra %
3/12	×1.031	+3.1%
4/12	×1.054	+5.4%
6/12	×1.118	+11.8%
8/12	×1.202	+20.2%
12/12	×1.414	+41.4%

❓ Frequently Asked Questions

+How many bundles per square?

3 bundles = 1 square (100 sq ft) for standard shingles. Some premium shingles need 4-5 bundles per square.

+How do I find my roof pitch?

From the attic, hold a level at 12" horizontal and measure the vertical rise. 6" rise = 6/12 pitch. Or use a smartphone inclinometer app.

+How long do shingles last?

3-tab asphalt: 15-20 years. Architectural: 25-30 years. Metal standing seam: 40-70 years. Tile/slate: 50-100 years.

+Can I shingle over existing shingles?

Only over ONE existing layer. Two or more layers must be torn off. Best practice is always full tear-off for proper inspection.