📐 Roof Pitch Calculator – Angle, Slope %, Ratio & Factor
Advanced calculator for roof pitch ratio, slope %, angle, pitch factor & ridge height
Enter your roof’s rise (vertical height per 12 inches run) and run (horizontal distance). This tool computes pitch ratio, slope percentage, angle in degrees, pitch factor, and optional ridge height (with span). Perfect for roofers, architects, estimators, and homeowners planning materials, ventilation, safety, and design aesthetics.
Enter the vertical rise in inches. Example: 6 means the roof rises 6 inches for every 12 inches run. Standard run = 12 inches. You can change it if measuring differently. Enter the total building span in feet (gable-to-gable). Used to calculate ridge height.Result will appear here
💡 Tip: A 6:12 pitch ≈ 26.6° and is the most common U.S. residential slope.
📐 Roof pitch classification will appear here after calculation.
✅ Best Practices for Measuring & Using Roof Pitch:
• Always measure rise per 12-inch run for accuracy.
• Take multiple measurements across sections (valleys, hips, dormers).
• Use pitch gauges, angle finders, or digital apps.
• Ridge-to-eave measurement improves attic space estimates.
• Convert pitch factor × footprint to get surface area for shingles.
• Steeper slopes (>6:12) require more safety gear and labor.
• Low slope (<3:12) needs membranes (TPO, EPDM, bitumen).
• Very steep (>12:12) often requires scaffolding or rope systems.
• Climate matters: snow regions = steeper; hot = moderate.
• Check local codes for minimum pitch allowed for shingles.
• Consider aesthetics — modern = low, chalet = steep, colonial = medium.
• Round up when ordering to avoid shortages.
❓ Extended FAQ - Roof Pitch Insights
Q: What are common roof pitches?
4:12 (~18°), 6:12 (~26°), 9:12 (~36°).
Q: How do I convert ratio to degrees?
Angle = arctan(rise ÷ run). Example: 6:12 ≈ 26.57°.
Q: Why is pitch factor important?
It adjusts flat area to actual surface — key for shingles & underlayment.
Q: Can I use shingles on low slope?
Not below 2:12 without special underlayment.
Q: What’s ridge height?
Ridge height = (rise/run) × (½ span). Example: span 30ft, 6:12 pitch → ridge ≈ 7.5ft.
Q: How does pitch affect cost?
Steeper = more material, waste, labor, and higher insurance.
Q: Which slope is best by climate?
Snowy = steep (>6:12). Hot = moderate (4–6:12) for ventilation.
Q: What’s too steep?
>12:12 (45°+) is rare, dangerous, and costly.
Q: Do insurance companies care?
Yes — steeper roofs mean higher risk & premiums.