📐 Roof Pitch Calculator – Roof Slope %, Angle (°), Ratio & Factor
Free online tool to calculate roof pitch from rise/run. Get slope percentage, degrees, pitch ratio (e.g. 6:12), roof pitch factor, and ridge height. Includes chart, code requirements, and how-to tips.
The roof pitch calculator instantly converts rise and run into roof slope, angle, ratio, and pitch factor. It’s also a roof slope percent calculator and roof pitch angle calculator in one. Enter two measurements — or select a preset — and see how pitch affects materials, cost, and ventilation.
Knowing your roof pitch helps plan roofing materials, drainage, and attic space. You can also estimate shingle coverage by multiplying area by the pitch factor. This calculator provides everything from rise over run conversion to ridge height estimation.
📊 Enter Roof Dimensions
Example: a 6″ rise per 12″ run means a 6:12 roof pitch. Default run = 12″, the industry standard for calculating slope. Enter total building width (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.
🧠 Understanding Roof Pitch
Roof pitch is the ratio of rise over run. For example, a 6:12 roof pitch means the roof rises 6 inches for every 12 inches of horizontal distance. It can be expressed in:
- 📈 Pitch ratio (e.g. 6:12)
- 📏 Slope percentage = rise ÷ run × 100
- 📐 Angle (degrees) = arctangent(rise/run)
Roof pitch affects drainage, shingle overlap, attic ventilation, and visual style. Steeper roofs are better for snow, while low slopes suit modern designs and warm climates.
📊 Roof Pitch Conversion Chart
| Pitch (Rise:Run) | Degrees (°) | Slope % | Pitch Factor |
|---|---|---|---|
| 3:12 | 14.0° | 25% | 1.031 |
| 4:12 | 18.4° | 33% | 1.054 |
| 5:12 | 22.6° | 42% | 1.083 |
| 6:12 | 26.6° | 50% | 1.118 |
| 8:12 | 33.7° | 67% | 1.202 |
| 9:12 | 36.9° | 75% | 1.25 |
| 12:12 | 45° | 100% | 1.414 |
Use the pitch factor to convert roof footprint into surface area (square footage × factor = total roofing area). Example: 1,000 sq ft at 6:12 pitch → 1,118 sq ft actual roof surface.
✅ Best Practices for Measuring & Using Roof Pitch
- Use a digital angle finder or smartphone app for accuracy.
- Take measurements from multiple sections (eaves, dormers, valleys).
- Check code: shingles allowed ≥2:12; underlayment required below 4:12.
- Steep pitches (>8:12) increase waste, cost, and safety risk.
- Low slopes (<3:12) need membrane systems (TPO, EPDM).
- Use Roof Shingles Calculator to plan bundles by pitch factor.
- Pair with Roof Area Calculator to estimate total square footage.
- Always round up on materials — leftover bundles beat shortages.
🔗 Related Roofing Calculators
❓ Extended FAQ – Roof Pitch Insights
Q: What is a roof pitch calculator?
It converts rise/run to slope %, degrees, and ratio. Useful for estimating roof surface, drainage, and shingle requirements.
Q: How do I measure roof pitch safely?
From attic: measure 12″ along a rafter and note vertical rise. Or outside with a level and ruler — then input numbers above.
Q: What’s the ideal roof pitch for shingles?
4:12–6:12 is most common; steeper = more labor, flatter = membrane needed.
Q: Can I find roof pitch in degrees?
Yes. The calculator converts to degrees automatically (e.g., 6:12 ≈ 26.6°).