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Roof Pitch Chart: Slope, Degrees, Multiplier & Rafter Length
Complete reference for every common roof pitch from 1/12 to 24/12 — angle in degrees, slope percentage, pitch multiplier for area calculations, and rafter length per foot of run. Free for contractors, framers, architects, and homeowners.
Complete Roof Pitch Chart
Pitch ratio is rise over run normalized to 12 inches of run. Multiplier is the factor that converts footprint area to actual roof surface area. Rafter length is the length of rafter per foot of horizontal run, used for layout and cut math.
| Pitch | Degrees | Slope % | Multiplier | Rafter / Ft | Typical Use |
|---|---|---|---|---|---|
| 1/12 | 4.76° | 8.3% | 1.003 | 12.04 in | Low-slope: requires built-up, TPO, EPDM, or modified bitumen — not shingle territory |
| 2/12 | 9.46° | 16.7% | 1.014 | 12.17 in | Minimum for shingles with double-layer underlayment or self-adhered membrane |
| 3/12 | 14.04° | 25.0% | 1.031 | 12.37 in | Low-slope shingle with manufacturer-approved low-slope assembly |
| 4/12 | 18.43° | 33.3% | 1.054 | 12.65 in | Standard shingle threshold; mid-century ranch and modern minimalist homes |
| 5/12 | 22.62° | 41.7% | 1.083 | 13.00 in | Common residential pitch; sheds water well in moderate climates |
| 6/12 | 26.57° | 50.0% | 1.118 | 13.42 in | Most-built North American residential pitch — colonial, craftsman, traditional |
| 7/12 | 30.26° | 58.3% | 1.158 | 13.89 in | Cape Cod, Tudor-influenced colonials; better attic space |
| 8/12 | 33.69° | 66.7% | 1.202 | 14.42 in | Steep slope threshold — labor premium kicks in (15 to 35% on labor) |
| 9/12 | 36.87° | 75.0% | 1.250 | 15.00 in | Steep Cape Cod, cottage, pitched-front colonial |
| 10/12 | 39.81° | 83.3% | 1.302 | 15.62 in | Steep slope; roof jacks and harnesses mandatory |
| 11/12 | 42.51° | 91.7% | 1.357 | 16.28 in | Tudor and Gothic Revival; substantial labor premium |
| 12/12 | 45.00° | 100.0% | 1.414 | 16.97 in | Steep 45-degree pitch; Tudor, Victorian, Gothic; +41% roof area |
| 14/12 | 49.40° | 116.7% | 1.537 | 18.44 in | Architectural steep — Victorian turrets, A-frame cottages |
| 16/12 | 53.13° | 133.3% | 1.667 | 20.00 in | Mansard and Gothic Revival; +67% roof area |
| 18/12 | 56.31° | 150.0% | 1.803 | 21.63 in | Steep architectural and historic-replication work |
| 20/12 | 59.04° | 166.7% | 1.943 | 23.32 in | Very steep; chapel, A-frame, alpine cabin styles |
| 24/12 | 63.43° | 200.0% | 2.236 | 26.83 in | Extreme architectural pitch; +124% roof area vs footprint |
Formulas: degrees = arctan(rise / 12) · slope % = (rise / 12) × 100 · multiplier = sqrt(rise² + 144) / 12 · rafter / ft = sqrt((rise/12)² + 1) × 12 inches
Quick Reference: Common Pitches
4/12 — Modern & Ranch
18.43 degrees, slope 33.3%, multiplier 1.054. The threshold pitch for standard asphalt shingle application. Common on mid-century ranch, modern minimalist, and porches. Drains adequately but not ideal for heavy snow. Multiplier means roof area is only 5% larger than footprint.
6/12 — Most Common
26.57 degrees, slope 50.0%, multiplier 1.118. The most-built residential pitch in North America. Standard for colonials, craftsman bungalows, and traditional homes. Provides usable attic space, sheds water well, accepts every shingle product without low-slope underlayment requirements.
8/12 — Steep Slope Threshold
33.69 degrees, slope 66.7%, multiplier 1.202. Where most contractors begin charging a steep-slope premium because productivity drops 25 to 40 percent and roof jacks become mandatory. Common on Cape Cod, cottage, and pitched-front colonial. Roof area is 20% larger than footprint.
12/12 — 45 Degrees
45 degrees exactly, slope 100.0%, multiplier 1.414. Standard high pitch for Tudor, Victorian, and Gothic Revival architecture. Roof area is 41% larger than footprint, with substantial labor premium. Sheds snow effectively and creates dramatic interior volumes over open spaces.
Pitch Math: Tips and Common Mistakes
Always normalize to 12 inches of run
If you measure rise over a 24-inch level, divide by 2. Pitch notation always uses 12 inches of run regardless of how you measured. A 5-inch rise over 10 inches of run is 6/12 once normalized.
Apply the multiplier before pricing material
Footprint area times pitch multiplier equals true roof surface. Skipping this step under-orders shingles by 5 to 41 percent depending on pitch.
Watch the 4/12 underlayment threshold
Slopes between 2/12 and 4/12 require a double-layer underlayment or self-adhered membrane under shingles. Quote it correctly or risk warranty issues.
Do not confuse pitch ratio with slope percentage
Slope percentage (rise / run × 100) is used in commercial low-slope work. Pitch ratio is the residential standard. A 50 percent slope equals a 6/12 pitch.
Check pitch consistency across the roof
Older homes often have shed dormers or additions at different pitches. Measure each plane separately and apply the matching multiplier.
Roof Pitch Chart FAQs
Q:What is roof pitch?
A: Roof pitch is the slope expressed as a ratio of vertical rise to horizontal run, normalized to 12 inches of run. A 6/12 pitch means six inches of rise for every twelve inches of run. North American roofers, framers, architects, and inspectors all use this notation because it ties directly to material quantities, code compliance, structural calculations, and safety planning.
Q:What is the most common roof pitch?
A: 6/12 (26.57 degrees) is the most-built residential pitch in North America. It sheds water well, provides usable attic space, accepts every shingle product without low-slope underlayment requirements, and balances installation cost against weather performance. Most colonial, craftsman, and traditional residential roofs land at 5/12 to 7/12.
Q:How do I convert roof pitch to degrees?
A: Take arctangent of (rise divided by 12). For 6/12: atan(6/12) = atan(0.5) = 26.57 degrees. Common conversions are in the table above: 3/12 = 14.04°, 4/12 = 18.43°, 5/12 = 22.62°, 6/12 = 26.57°, 8/12 = 33.69°, 10/12 = 39.81°, 12/12 = 45°.
Q:What is the pitch multiplier used for?
A: The pitch multiplier converts a building footprint area into actual roof surface area. Formula: sqrt(rise² + run²) divided by run. For 6/12: sqrt(36 + 144) / 12 = 1.118. A 1,500 SF footprint becomes 1,677 SF of actual roof at 6/12 pitch. All shingle, metal, and tile pricing is denominated by actual roof area, not footprint — so applying the multiplier is mandatory before quoting material.
Q:What pitch is too steep for asphalt shingles?
A: Standard asphalt shingles are rated for slopes of 4/12 (18.43°) and steeper using normal application. Between 2/12 and 4/12, shingles need a low-slope underlayment system — double-layer underlayment or self-adhered membrane. Below 2/12, shingles are not appropriate; the roof needs a low-slope system (TPO, EPDM, modified bitumen, built-up). There is no high-pitch limit on asphalt shingles, but steep slopes over 8/12 add labor premium and safety equipment.
Q:When does a steep-slope premium kick in?
A: 8/12 (33.69 degrees) is the industry threshold where most contractors begin charging a steep-slope premium. Productivity drops 25 to 40 percent because crews need roof jacks, harnesses, and slower installation pace. Typical surcharge is $0.50 to $2.00 per SF on labor, or a 15 to 35 percent total labor premium.
Q:How do I measure pitch on an existing roof?
A: Hold a 24-inch level horizontally against the roof, with one end touching the surface. Measure vertically from the level down to the roof surface at the 12-inch mark. That number is your rise per foot of run. A 12-inch drop over 24 inches equals a 6/12 pitch. Always measure on a straight rafter run — not over hips, valleys, or ridge caps.
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