Pitch formulas
- Pitch (in/12) = (rise÷run) × 12
- Degrees = arctan(rise÷run) × 180/π
- Area factor = √(1 + (rise÷run)²)
A 6/12 pitch rises 6 inches for every 12 inches of run—about 26.6°. Multiply horizontal plan area by the area factor to estimate roof surface for shingles. Continue with the roofing shingles calculator.
Worked example
Rise 8", run 12" → pitch 8/12, angle ≈ 33.7°, area factor ≈ 1.202. A 40 × 25 ft plan footprint has 1,000 sq ft horizontal and about 1,202 sq ft of roof surface before dormers and overhangs.
Measuring safely
Prefer attic rafter measurements or drawings when possible. Roof surfaces are fall hazards—read how to measure roof pitch before climbing.
Common mistakes
- Using degrees when a supplier asks for X-in-12 pitch.
- Forgetting that hips, valleys, and overhangs add surface beyond a simple rectangle.
| Pitch | Approx. degrees | Multiplier |
|---|---|---|
| 3/12 | 14.0° | 1.031 |
| 4/12 | 18.4° | 1.054 |
| 6/12 | 26.6° | 1.118 |
| 8/12 | 33.7° | 1.202 |
| 12/12 | 45.0° | 1.414 |
Assumptions and limits
The roof pitch calculator results are planning estimates for rectangular or cylindrical shapes with uniform depth. Real sites have slopes, voids, and product variation. Always confirm coverage with the manufacturer label and local building practices before you buy large quantities.
Unit toggles switch input labels between US imperial and metric. Shareable URLs store your inputs in the query string for convenience, while the canonical tag stays on the clean page URL so search engines do not index every parameter combination.
Shopping checklist
- Write down the calculator outputs (volume, bags, or piece counts) and round up for waste.
- Call your supplier for density, dye lot, or delivery minimums when ordering bulk material.
- Check access for trucks, wheelbarrows, and staging space before delivery day.
- Photograph existing conditions so you can revisit dimensions if a helper measures differently.
Record pitch as X-in-12 when talking to suppliers—many shingle specifications use that form instead of degrees.
FAQ
What is a 6/12 roof pitch?
The roof rises 6 inches for every 12 inches of horizontal run—about 26.6°, a common residential slope.
How do I measure pitch safely?
Measure on a rafter, rake board, or level+tape on the roof surface using safe access. See our measurement guide before climbing.
Related guides
Sources
- FEMA – Roof and building guidance (general) Used for: General roof slope terminology; measure safely from the ground when possible. Checked .
Estimates only—confirm bag yields on the product label and check local building codes before you pour or order. Not affiliated with QUIKRETE, Sakrete, Sonoco, or any manufacturer named in the sources. Found an error? Tell me.
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