Roof Pitch Chart
Every pitch from 1/12 to 24/12 with degrees, percent slope, pitch factor, hip/valley rafter factor, rafter sizing, material compatibility, climate guidance, and labor cost multipliers. The only roof pitch reference you need.
Master Roof Pitch Chart: 1/12 to 24/12
This is the most complete roof pitch reference table available. Every standard pitch is listed with its degree angle, percent slope, pitch factor (for roof area), hip/valley rafter factor, approximate rafter length per 12-inch run, OSHA category, and pitch category. Use the pitch factor column when ordering materials and the hip/valley factor when cutting hip or valley rafters.
| Pitch (X/12) | Degrees | % Slope | Pitch Factor | Hip/Valley Factor | Rafter / 12″ Run | OSHA Class | Category |
|---|---|---|---|---|---|---|---|
| 1/12 | 4.76 | 8.3% | 1.003 | 1.416 | 12.04″ | Low-slope | Flat |
| 2/12 | 9.46 | 16.7% | 1.014 | 1.424 | 12.17″ | Low-slope | Low |
| 3/12 | 14.04 | 25.0% | 1.031 | 1.436 | 12.37″ | Low-slope | Low |
| 4/12 | 18.43 | 33.3% | 1.054 | 1.453 | 12.65″ | Low-slope | Conventional |
| 5/12 | 22.62 | 41.7% | 1.083 | 1.474 | 13.00″ | Low-slope | Conventional |
| 6/12 ★ | 26.57 | 50.0% | 1.118 | 1.500 | 13.42″ | Low-slope | Conventional |
| 7/12 | 30.26 | 58.3% | 1.158 | 1.530 | 13.89″ | Steep-slope | Conventional |
| 8/12 | 33.69 | 66.7% | 1.202 | 1.564 | 14.42″ | Steep-slope | Steep |
| 9/12 | 36.87 | 75.0% | 1.250 | 1.601 | 15.00″ | Steep-slope | Steep |
| 10/12 | 39.81 | 83.3% | 1.302 | 1.642 | 15.62″ | Steep-slope | Steep |
| 11/12 | 42.51 | 91.7% | 1.357 | 1.685 | 16.28″ | Steep-slope | Steep |
| 12/12 | 45.00 | 100.0% | 1.414 | 1.732 | 16.97″ | Steep-slope | Steep |
| 14/12 | 49.40 | 116.7% | 1.537 | 1.833 | 18.44″ | Steep-slope | Very Steep |
| 16/12 | 53.13 | 133.3% | 1.667 | 1.944 | 20.00″ | Steep-slope | Very Steep |
| 18/12 | 56.31 | 150.0% | 1.803 | 2.060 | 21.63″ | Steep-slope | Very Steep |
| 20/12 | 59.04 | 166.7% | 1.944 | 2.182 | 23.32″ | Steep-slope | Very Steep |
| 24/12 | 63.43 | 200.0% | 2.236 | 2.449 | 26.83″ | Steep-slope | Very Steep |
★ Most common US residential pitch. Pitch Factor = sqrt(1 + (rise/12)^2). Hip/Valley Factor = sqrt(Pitch Factor^2 + 1) / sqrt(2) x sqrt(2) = sqrt((rise/12)^2 + 2). Rafter per 12″ run = 12 x Pitch Factor. OSHA steep-slope threshold is 7/12 (29 CFR 1926.500).
How to Read a Roof Pitch Chart
A roof pitch chart contains several different expressions of the same underlying geometry. Understanding what each column means lets you use the chart correctly for every application – material ordering, rafter layout, structural engineering, and contractor communication.
The standard US notation. The first number is vertical rise in inches; the second is always 12, representing 12 inches of horizontal run. A 6/12 pitch rises 6 inches vertically for every 12 inches horizontally. This is what appears on blueprints, manufacturer specs, and building permits.
The same pitch is sometimes written with a colon (6:12) instead of a slash. Both mean exactly the same thing. Architects occasionally use the decimal form (0.500 for 6/12) in structural calculations.
The trigonometric equivalent of the pitch ratio. Calculated as arctan(rise / 12) x (180 / pi). Used by structural engineers, smartphone inclinometer apps, speed squares, and metric-system countries. A 6/12 pitch = 26.57 degrees. A 12/12 pitch = exactly 45 degrees.
The key threshold: OSHA defines “steep-slope” as any roof above 4:12 (18.4 degrees) for fall protection planning. Most manufacturers also use 4/12 as the minimum for standard shingle installation.
The most important column for material ordering. Multiply your building footprint by the pitch factor to get the true sloped surface area. Formula: sqrt(1 + (rise/12)^2). At 6/12, the factor is 1.118 meaning every 1,000 sq ft of floor plan corresponds to 1,118 sq ft of actual roof surface.
Skipping this step and ordering by footprint area causes a 5% shortfall at 4/12, 12% at 7/12, and 41% at 12/12. The error compounds significantly at steep pitches.
The hip/valley rafter factor converts the horizontal run of a hip or valley rafter to its actual length. It accounts for the fact that hip and valley rafters run at 45 degrees in plan, adding diagonal length on top of the pitch length. Formula: sqrt((rise/12)^2 + 2).
For a 6/12 pitch, the hip/valley factor is 1.500. If your hip rafter has a 10-foot horizontal run, the actual rafter length is 10 x 1.500 = 15.0 feet. This column is what separates a useful professional reference from a basic pitch chart.
The Formula Behind Every Column
Visual Roof Pitch Comparison
The profiles below are drawn to accurate proportional geometry for each pitch. All triangles share the same base width so you can directly compare how the roofline height changes as pitch increases. The most common pitch (6/12) is highlighted in teal.
Teal = conventional range (4/12-6/12) | Orange outline = steep-slope OSHA zone (7/12-11/12) | Red outline = very steep (12/12+)
Roofing Material Compatibility by Pitch
Material selection is one of the most consequential decisions your pitch controls. Installing below the manufacturer’s minimum pitch voids the warranty on day one. The table below shows compatibility for every major roofing material against each pitch range, based on 2021 IRC requirements and 2026 manufacturer specifications from GAF, CertainTeed, Metal Sales, and NRCA technical bulletins.
| Roofing Material | Flat (1-2/12) | Low (3/12) | Conv. (4-6/12) | Steep (7-12/12) | Very Steep (14+/12) | Min. Pitch | 2026 Cost/sq |
|---|---|---|---|---|---|---|---|
| TPO Membrane | YES | YES | MOD | NO | NO | 1/4:12 | $150-$280 |
| EPDM Rubber Membrane | YES | YES | MOD | NO | NO | 1/4:12 | $120-$250 |
| Modified Bitumen | YES | YES | MOD | NO | NO | 1/4:12 | $130-$220 |
| Standing Seam Metal | SPEC | YES | YES | YES | YES | 1:12 (1/4:12 mechanically seamed) | $360-$620 |
| Exposed Fastener Metal Panel | NO | YES | YES | YES | YES | 3:12 | $180-$320 |
| Asphalt 3-Tab Shingles | NO | NO | YES | YES | MOD | 4:12 (MOD at 2:12) | $80-$120 |
| Asphalt Architectural Shingles | NO | NO | YES | YES | YES | 4:12 (MOD at 2:12) | $95-$145 |
| Cedar Shake / Wood Shingle | NO | NO | YES | YES | YES | 4:12 (6:12+ recommended) | $280-$440 |
| Clay / Concrete Tile | NO | NO | YES | YES | MOD | 4:12 (2.5:12 low-profile tile) | $300-$500 |
| Synthetic Slate / Composite | NO | MOD | YES | YES | YES | 3:12 | $250-$400 |
| Natural Slate | NO | NO | MOD | YES | YES | 4:12 (6:12+ standard) | $600-$1,200 |
For a detailed breakdown of metal roofing options by pitch, see the metal roof cost calculator. For converting your pitch to the exact square footage you need to order, use the roof square footage calculator.
Hip and Valley Rafter Factor: The Column Most Charts Leave Out
The hip/valley rafter factor is the most commonly omitted column in basic pitch charts, yet it is essential for any hip roof, intersecting gable roof, or dormer framing. Without it, hip and valley rafter lengths must be calculated from scratch using three-dimensional trigonometry. This chart eliminates that step.
What the Hip/Valley Factor Does
A hip or valley rafter runs diagonally in plan at 45 degrees to the wall plates. This means its horizontal run is longer than the common rafter run by a factor of the square root of 2. The hip/valley factor combines this diagonal plan projection with the pitch angle to give a single multiplier you apply to the horizontal run of the hip or valley.
| Pitch (X/12) | Common Rafter Factor | Hip/Valley Factor | Hip vs Common Ratio | 10 ft Run: Common | 10 ft Run: Hip/Valley |
|---|---|---|---|---|---|
| 4/12 | 1.054 | 1.453 | 1.379x longer | 10.54 ft | 14.53 ft |
| 5/12 | 1.083 | 1.474 | 1.361x longer | 10.83 ft | 14.74 ft |
| 6/12 | 1.118 | 1.500 | 1.342x longer | 11.18 ft | 15.00 ft |
| 7/12 | 1.158 | 1.530 | 1.321x longer | 11.58 ft | 15.30 ft |
| 8/12 | 1.202 | 1.564 | 1.302x longer | 12.02 ft | 15.64 ft |
| 9/12 | 1.250 | 1.601 | 1.281x longer | 12.50 ft | 16.01 ft |
| 10/12 | 1.302 | 1.642 | 1.261x longer | 13.02 ft | 16.42 ft |
| 12/12 | 1.414 | 1.732 | 1.225x longer | 14.14 ft | 17.32 ft |
Rafter Sizing by Pitch: IRC 2021 Span Guide
Rafter size depends on pitch, span, species, grade, and load. The table below shows maximum allowable spans for the most common lumber size and species combinations at standard residential roof loads (20 psf live load, 10 psf dead load) per IRC 2021 Table R802.4.1. Spans are for 16-inch on-center spacing in climate zones with no extraordinary snow load.
| Lumber Size | Species / Grade | Max Span at 4/12+ | Max Span at 7/12+ | Max Span at 12/12+ | Notes |
|---|---|---|---|---|---|
| 2×6 | SPF #2 | 11′ 4″ | 12′ 9″ | 14′ 0″ | Most common residential rafter size 4/12 to 7/12 |
| 2×6 | Doug Fir-Larch #2 | 12′ 6″ | 14′ 1″ | 15′ 5″ | Strongest common 2×6 species |
| 2×8 | SPF #2 | 15′ 0″ | 16′ 10″ | 18′ 6″ | Standard for 8/12 to 12/12 on moderate spans |
| 2×8 | Doug Fir-Larch #2 | 16′ 6″ | 18′ 7″ | 20′ 4″ | Preferred for steep pitches over 20 ft spans |
| 2×10 | SPF #2 | 19′ 0″ | 21′ 5″ | 23′ 6″ | Wide low-slope barn and commercial spans |
| 2×10 | Doug Fir-Larch #2 | 21′ 0″ | 23′ 8″ | 25′ 11″ | Maximum prescriptive residential rafter span |
| 2×12 | SPF #2 | 23′ 3″ | 26′ 2″ | 28′ 8″ | Requires engineering analysis in most jurisdictions |
Spans increase with steeper pitch because the rafter’s horizontal span (run) is shorter relative to its length as pitch increases. A 15-ft rafter at 12/12 pitch has only a 10.6-ft horizontal run vs. a 14.2-ft horizontal run at 4/12 pitch. The structural load calculation uses the horizontal span, so steeper roofs can span further with the same lumber.
Labor Cost Multipliers by Pitch
Roof pitch is one of the biggest drivers of installed cost beyond material selection. Labor premiums apply for two reasons: steeper roofs require more safety equipment and slower movement, and they create more actual surface area per square foot of building footprint. The table below shows 2026 national average cost ranges and the multiplier contractors typically apply relative to a baseline 4/12 pitch.
| Pitch Range | Labor Multiplier | Installed Cost (asphalt arch) | Relative Cost | Key Driver |
|---|---|---|---|---|
| 2/12 – 3/12 (Low-slope) | 0.90x | $320 – $440 per sq | Requires membrane materials; slow drainage risk | |
| 4/12 – 6/12 (Baseline) | 1.00x | $380 – $520 per sq | Standard crew, standard safety, most competitive | |
| 7/12 – 9/12 (OSHA steep) | 1.15x – 1.25x | $440 – $650 per sq | OSHA fall protection required; roof jacks needed | |
| 10/12 – 12/12 (Steep) | 1.30x – 1.50x | $490 – $780 per sq | Harness systems, scaffolding, higher waste factor | |
| 14/12 – 16/12 (Very steep) | 1.60x – 2.00x | $600 – $1,040 per sq | Rope access or boom lift; most crews surcharge heavily | |
| 18/12+ (Extreme) | 2.00x – 2.50x+ | $760 – $1,300+ per sq | Specialist crews only; scaffolding typically required |
Low-slope roofs (2/12 to 3/12) are easier to walk and faster to install per square than steep roofs, but they require membrane materials (TPO, EPDM) that cost more per square than asphalt shingles. The net effect is that installed cost per square often runs similar to or higher than a conventional 5/12 to 6/12 shingle roof, depending on the membrane system.
Cost multipliers apply to the actual sloped area, not the footprint. A 12/12 roof on the same building footprint has 34% more surface area than a 6/12 roof (pitch factor 1.414 vs 1.118), and carries a 1.30x to 1.50x labor premium. The combined effect means total installed cost can be 70 to 100% higher than the same building at a conventional pitch.
Recommended Roof Pitch by Climate Zone
Climate is the most important regional factor in pitch selection. What performs perfectly in Phoenix will underperform in Minnesota and vice versa. The guidance below draws from ASCE 7-22 structural load maps, IRC climate zone designations, and regional contractor experience for the four primary climate factors that affect pitch selection.
States most affected: Maine, Vermont, New Hampshire, upstate New York, Michigan’s Upper Peninsula, Wisconsin, Minnesota, Montana, Wyoming, Colorado (above 6,000 ft elevation), northern Idaho.
IRC requirement: Ground Snow Load above 25 psf triggers engineering analysis for all roof framing regardless of pitch.
A 6/12 pitch evacuates water roughly 60% faster than a 3/12 pitch on the same building under the same rainfall intensity because steeper slopes reduce the horizontal distance water must travel before reaching the eave.
The Pacific Northwest also sees heavy moss growth on anything below 7/12 in shaded exposures. Steeper pitches dry faster after rain and resist moss significantly better.
Hip roofs outperform gable roofs in high-wind zones at any pitch because they eliminate the large vertical gable end wall that acts as a sail. A 4/12 to 5/12 hip roof is the optimal combination for hurricane-prone areas per FHWA and IBHS research.
Florida Building Code (adopted 2026 revision): Requires engineered uplift connections at every rafter-to-plate and rafter-to-ridge joint for any new construction in Wind Zones II and III.
Flat and very low-slope roofs in desert climates need engineered drainage because even modest rainfall can pool when slopes approach 1/12. A minimum 2% slope to drains is required by IBC for commercial flat roofs and recommended for residential applications.
| US Region | Dominant Climate Factor | Recommended Pitch Range | Common Material Choice | Code / Standard |
|---|---|---|---|---|
| Northeast (ME, VT, NH, NY, MA) | Heavy snow + ice dams | 9/12 – 12/12 | Architectural shingles, slate, standing seam | IRC + local snow load |
| Upper Midwest (MN, WI, MI) | Heavy snow + cold | 8/12 – 12/12 | Architectural shingles, metal panel | IRC Zone 7-8 |
| Pacific Northwest (WA, OR) | Heavy rain + moss | 6/12 – 9/12 | Metal, composite slate, cedar shake | IRC Zone 5-6 |
| Mountain West (CO, UT, WY above 6k ft) | Heavy snow + UV | 10/12 – 14/12 | Standing seam metal, synthetic slate | ASCE 7 + local |
| Mid-Atlantic (VA, MD, PA, NJ) | Mixed snow + rain | 6/12 – 9/12 | Architectural shingles | IRC Zone 4-5 |
| Southeast (GA, SC, NC) | Moderate rain + humidity | 5/12 – 8/12 | Architectural shingles, metal | IRC Zone 3-4 |
| Gulf Coast (TX, LA, MS, AL, FL Gulf) | High wind + rain | 4/12 – 6/12 hip roof | Impact-rated shingles, metal | ASCE 7 Wind Zone II-III |
| Florida Peninsula | Extreme wind + rain | 4/12 – 5/12 hip roof | Concrete tile, standing seam | Florida Building Code |
| Desert Southwest (AZ, NV, NM, west TX) | Heat + UV | 3/12 – 5/12 | Tile, metal, TPO | IRC Zone 2-3 |
| California Coast | Moderate / fire zone | 4/12 – 7/12 | Class A rated: concrete tile, metal | California CBC + fire code |
Roof Pitch by Architectural Style
Architectural style is the second major driver of pitch selection after climate. Each style has a characteristic pitch range rooted in its historical origin, structural requirements, and visual proportions. Using an out-of-range pitch on a style-specific home creates proportional awkwardness that is immediately apparent even to non-architects. The guide below shows the canonical pitch range for every major US residential style.
How to Measure Roof Pitch: 4 Methods
Before you can use any pitch chart, you need your actual pitch. These four methods cover every common field situation from new construction layout to measuring an existing home for a re-roof estimate, ranked from most accurate to least accurate.
Go into the attic. Hold a 12-inch level horizontally against the underside of a rafter with one end touching the rafter. Center the bubble. At the 12-inch mark on the level, measure straight down from the level to the underside of the rafter. That measurement in inches is your rise. Your pitch is rise/12.
Accuracy: Within 1/8 inch of true pitch. This is the only method accurate enough for framing cuts.
From the roof deck or a ladder at the eave, hold a 12-inch level horizontally against the roof surface. At the 12-inch mark, pivot a speed square with its pivot point touching the level and the square’s leg along the roof surface. Read the pitch directly from the degree scale marked on the square.
Accuracy: Within 0.5 degrees (about 0.1 rise). Good for material estimates, not framing cuts.
Stand at the gable end of the building. Hold the phone with the long edge flat against the roofline (fascia board or rake trim). Read the angle in degrees. Convert using: rise = round(12 x tan(angle in degrees x pi/180)).
Example: App reads 26.6 degrees. Rise = round(12 x tan(26.6 x 0.01745)) = round(12 x 0.501) = round(6.01) = 6. Pitch = 6/12.
Accuracy: Within 1 degree on a flat surface. Use for quick estimates only.
If you know the building width and ridge height above the top plate, you can calculate pitch without getting on the roof. Pitch = (ridge height / half-span) x 12.
Example: Building width 28 ft, ridge height above top plate 7 ft. Half-span = 14 ft. Pitch = (7 / 14) x 12 = 6/12.
Ridge height is measured from the underside of the ridge board to the top of the wall plate. Accuracy depends on how precisely you can measure ridge height from inside the attic.
Frequently Asked Questions About Roof Pitch Charts
What is the most common roof pitch in the US?
The most common residential roof pitch in the US is 6/12 (26.57 degrees). It accounts for roughly 30 to 40% of new residential construction, balancing water shedding, material compatibility, attic space, and aesthetics. The 4/12 and 5/12 pitches are the next most common, collectively covering the majority of ranch-style and suburban tract homes built since the 1970s. Regional variation is significant: the Northeast averages 8/12 to 10/12, the Sunbelt averages 3/12 to 5/12, and the Pacific Northwest clusters around 6/12 to 8/12.
How do I read a roof pitch chart?
Find your pitch in the X/12 column. Read across to find the degree equivalent (useful for smartphone apps and speed squares), percent slope (used in drainage engineering), pitch factor (multiply by your plan area to get sloped area for material ordering), and hip/valley factor (multiply by your hip rafter horizontal run to get actual hip rafter length). The pitch factor column is what you use most often for material estimates. Example: 6/12 pitch, 1,200 sq ft footprint – multiply 1,200 x 1.118 = 1,342 sq ft of actual roof surface, then divide by 100 to get 13.42 squares, then add 10% waste = 14.8 squares to order.
What is the pitch factor or slope factor on a roof pitch chart?
The pitch factor (also called slope factor or roof multiplier) is the number you multiply by your building footprint to get the actual sloped roof surface area. It equals the square root of (1 plus (rise/12) squared). At 6/12 pitch the factor is 1.118, meaning a roof with a 1,000 sq ft footprint has 1,118 sq ft of actual surface to cover with materials. At 4/12 the factor is 1.054 (only 5.4% more than footprint), while at 12/12 it is 1.414 (41.4% more). Always use sloped area, not footprint, when ordering roofing materials.
What is the hip and valley rafter factor on a roof pitch chart?
The hip/valley rafter factor converts the horizontal projected run of a hip or valley rafter to its actual length. Hip and valley rafters run diagonally at 45 degrees in plan view, so their horizontal run is longer than a common rafter by the square root of 2. The factor combines this diagonal plan projection with the pitch angle: hip/valley factor = sqrt((rise/12) squared + 2). At 6/12 pitch, the factor is 1.500. If your hip rafter has a 12-foot horizontal run, its actual length is 12 x 1.500 = 18 feet. This factor is absent from most basic pitch charts but is essential for any hip roof framing layout.
What roof pitch is best for snow?
Pitches of 10/12 (39.8 degrees) and steeper reliably shed snow under gravity before loads reach structural limits. ASCE 7-22 uses 10/12 as the practical benchmark for snow-shedding design in high-load regions (ground snow load above 25 psf). Between 6/12 and 9/12, snow sheds adequately in most US markets but can accumulate in prolonged storms in climate zones 6 to 8 enough to require ice dam prevention at eaves (heat cable or wide ice and water shield coverage). Below 6/12, roofs in heavy snow regions should be engineered to carry the full balanced and unbalanced snow load rather than assumed to shed it.
What is the minimum roof pitch for shingles?
The minimum pitch for standard asphalt shingle installation is 4/12 per the 2021 IRC (Section R905.2) and all major manufacturer warranties including GAF, CertainTeed, and Owens Corning. Between 2/12 and 4/12, a low-slope modification is required: double-layer ice and water shield covering the entire deck plus a manufacturer-approved low-slope installation method. Below 2/12, shingles are not permitted by any major manufacturer or the IRC and a continuous membrane system (TPO, EPDM, or modified bitumen) is required. Metal standing seam can go as low as 1/4:12 with mechanically double-locked seams and proper butyl sealant.
How do I convert roof pitch to degrees?
Use the arctangent formula: Degrees = arctan(rise divided by 12) x (180 divided by pi). Most scientific calculators have an arctan or atan function. Examples: 4/12 = arctan(4/12) x 57.296 = 18.43 degrees. 6/12 = arctan(6/12) x 57.296 = 26.57 degrees. 9/12 = 36.87 degrees. 12/12 = exactly 45 degrees. Or simply look up the pitch in the master chart at the top of this page. The degree column lists pre-calculated values for every standard pitch from 1/12 through 24/12.
How does roof pitch affect material cost?
Roof pitch affects total installed cost in two ways: surface area and labor rate. First, a steeper pitch means more actual surface area per square foot of building footprint – compare the pitch factor of 1.054 at 4/12 versus 1.414 at 12/12. That 12/12 roof has 34% more surface area to cover with materials. Second, labor rates increase with pitch because steeper roofs require fall protection equipment, slower movement, more safety setup time, and more material waste from off-angle cutting. Most contractors apply a labor surcharge starting at 7/12, with 1.15x to 1.25x for 7/12 to 9/12, 1.30x to 1.50x for 10/12 to 12/12, and up to 2.50x for pitches above 18/12.
Free Roofing Calculators
This pitch chart tells you what your pitch means. These calculators tell you what to do with it – from ordering materials to pricing a full roof replacement. All free, all updated for 2026, and all built around the same pitch formulas documented in this guide. If you are in Texas and need a licensed contractor to verify any of these calculations on-site, browse vetted roofers in Houston, Austin, and Dallas.