Build · Roofing
Convert rise and run into pitch X/12, degrees, percent slope, and a rafter-length teaser.
Solve pitch, angle, %, or the missing rise/run.
Input mode
Scenario templates
Common pitches
X:12
6/12
Degrees
26.57°
% slope
50%
Rafter line (½ span 24′)
12.58
Within the common residential band often cited around 4:12–9:12 (GAF). · Category: Conventional residential
Interactive 3D gable (6/12)
Drag to orbitRoof planes steepen as rise/run increases. Schematic only — not a framing model.
Need overhang or full span mode? Open the rafter calculator with pitch 6/12 prefilled.
| Pitch | Angle | Slope % | Line len (span 24′) |
|---|---|---|---|
| 4/12 | 18.4° | 33.3% | 11.86 |
| 6/12 ← | 26.6° | 50% | 12.58 |
| 9/12 | 36.9° | 75% | 14.06 |
Pitch as X/12, degrees, percent slope, and a rafter-length teaser from the same triangle — all shown together. Input modes solve rise+run, pitch+run, or pitch+rise. Annotated diagram + pitch compare table; deep-links to the rafter tool.
Does not replace
Supply yard
Starting points for planning — not a site-specific design. Footnotes point to sources on this page.
| Topic | Typical starting value | Source notes |
|---|---|---|
| Typical U.S. residential pitch band | Often about 4:12 to 9:12 | GAF contractor guidance on common residential slopes. |
| Absolute minimum for asphalt shingles | 2:12 (never below) | GAF; ARMA low-slope bulletin; CertainTeed Landmark applicator manual. |
| Low-slope asphalt application | 2:12 to <4:12 with special underlayment | GAF & ARMA — double-layer underlayment or approved self-adhered membrane. |
| Standard-slope underlayment band | 4:12 and steeper (product-specific) | CertainTeed slope definitions; always read the product sheet. |
Short DIY narratives. Numbers match the one-click scenario presets in the calculator (US units).
Searching for “roof pitch to degrees” or “6/12 to degrees”? Pitch X/12, angle in degrees, and percent slope are three labels for the same right triangle. Formula: angle° = arctan(rise ÷ run) × 180/π. For a classic 6/12 pitch, rise/run = 0.5 → ≈ 26.57° and 50% slope. A 4/12 is ≈ 18.43° (33.3%); 9/12 is ≈ 36.87° (75%). Enter rise and run (or pick a common pitch chip) and the result strip shows X:12, degrees, %, and a rafter-length teaser together. Need a dedicated converter landing? See also roof pitch to degrees.
Searchers often look for a “roof slope calculator” or “roof pitch calculator” — both describe rise over run. Pitch is commonly X/12; slope percent is (rise ÷ run) × 100. Measure vertical rise over a known horizontal run. On many roofs you can use a level and tape: mark 12 inches of run and read the rise to get pitch directly as X/12.
Asphalt shingle makers (GAF, CertainTeed) and ARMA agree: do not install asphalt shingles below 2:12. Between 2:12 and 4:12, expect low-slope underlayment rules. Local code and the specific product sheet still control.
Pitch12 = rise × (12 ÷ run). Angle° = arctan(rise ÷ run) × 180/π. Slope % = (rise ÷ run) × 100. Hypotenuse = √(rise² + run²).
Pitch is often written as X/12 (rise over 12 units of run). Slope may be expressed as a percent or a ratio. Both come from the same rise and run — this roof pitch / slope calculator shows X/12, degrees, and percent together.
Degrees = arctan(rise ÷ run) × 180/π. For an X/12 pitch, rise/run = X/12, so 6/12 ≈ 26.57°, 4/12 ≈ 18.43°, 9/12 ≈ 36.87°. Percent slope = (rise ÷ run) × 100 (6/12 = 50%). This page shows all three formats from the same inputs.
Measure vertical rise over a known horizontal run — inches are fine if both use the same unit. On many roofs you can use a level and tape: mark 12 inches of run and read the rise to get pitch directly as X/12.
Manufacturers generally allow asphalt shingles at 2:12 and above only with low-slope underlayment procedures. Below 2:12 — do not. Verify the product and local code.
No — it is a visual aid that responds to rise/run. Use engineered plans for framing.
We cite extension services, manufacturer guidance, and municipal/IRC reprints. This is not legal advice, not a substitute for a licensed engineer or architect, and not approval from your Authority Having Jurisdiction (AHJ). Adopted codes and product warranties vary by place and year — verify before you buy or cut.
States absolute minimum asphalt-shingle slope 2:12; 2:12 to <4:12 treated as low slope needing double underlayment; typical residential often 4:12–9:12.
Industry bulletin: asphalt shingles allowed 2:12 to <4:12 only with special underlayment; never below 2:12.
Manufacturer slope bands: do not apply shingles below 2/12; low slope below 4/12; standard 4/12 up to 21/12.
Full site bibliography: Sources hub.
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Stringer length + IRC R311.7 table on one screen.
