📐 Roof Pitch Calculator

Roof Pitch Calculator: Rise and Run to Angle, Angle to Pitch, Rafter

Enter your pitch three ways: rise over run (e.g., 5/12), angle in degrees, or actual rafter length with house span. Get pitch notation, degrees, multiplier for roofing area calculations, rafter length, slope category, DIY safety rating, and compatible roofing material guidance. Quick-select buttons for all standard US pitches.

📐 Pitch Input and Span for Rafter Length

■ Input Method

■ Quick-Select Common US Pitches

Rise (inches, per 12-in run)

Run (always 12 in US)

■ House Span (for Rafter Length Output)

Full House Width (span) (from exterior wall to exterior wall, including overhangs)

📐

Your roof pitch results appear here

Enter pitch three ways: rise and run (e.g., 5 rise per 12 run), degrees from a digital angle gauge, or actual rafter length with half-span to back-calculate your pitch. Use the quick-select buttons for instant US standard pitch presets. Results include pitch notation, angle, multiplier for roofing calculations, rafter length, slope category, and compatible roofing materials.

Roof Pitch Summary

5/12 pitch notation

22.6 degrees

1.083 pitch multiplier

📐 Complete Pitch Data

Pitch notation —

Angle in degrees —

Pitch multiplier (for roofing area) —

Rise per 12 in run —

100 sq ft floor = this much roof —

Rafter length (span / 2 x multiplier) —

Slope Category

Category —

DIY safety —

Asphalt shingles —

Metal roofing (standing seam) —

Corrugated / R-panel (screw-down) —

Underlayment overlap requirement —

Pitch Geometry Diagram

Pitch Multiplier vs Standard US Pitches (Your Pitch Highlighted)

US Roof Pitch Notation, Angle Conversion, and the Pitch Multiplier for Roofing Area Calculations

In the United States, roof pitch is expressed as a ratio of rise to run, where the run is always 12 inches. A 5/12 pitch rises 5 inches for every 12 inches of horizontal distance. This notation is unique to US and Canadian construction; most European countries express roof slope as a percentage or in degrees. Understanding this distinction is important when referencing international roofing materials or working with imported framing tables, which may use percentage slope (5/12 = 41.7 percent, calculated as rise/run x 100).

The pitch multiplier is the number by which you multiply your horizontal roof footprint area to get the actual sloped roof surface area. For a 5/12 pitch, the multiplier is 1.083, which means 100 square feet of house footprint equals 108.3 square feet of actual sloped roof surface. This is the critical conversion factor needed for ordering shingles, metal roofing panels, and underlayment. The multiplier is derived from the Pythagorean theorem: for a rise of 5 and a run of 12, the hypotenuse (the sloped surface) is sqrt(25+144) = 13.0 inches. The multiplier is 13.0/12 = 1.083.

Standard US Residential Roof Pitches and Their Properties

Pitch	Degrees	Multiplier	Common Use in US	Slope Category
2/12	9.46	1.014	Flat commercial, EPDM roofs	Very low
3/12	14.04	1.031	Ranch homes, additions	Low slope
4/12	18.43	1.054	Ranch homes, wide-span buildings	Low-moderate
5/12	22.62	1.083	Most common US residential pitch	Moderate
6/12	26.57	1.118	Cape Cod, traditional colonials	Moderate
7/12	30.26	1.158	Traditional colonial, steeper look	Medium-steep
8/12	33.69	1.202	Tudor, steep gable homes	Steep
9/12	36.87	1.250	Victorian, high-style residential	Steep
12/12	45.00	1.414	A-frames, very steep Victorians	Very steep

Three Ways to Find Your Roof Pitch

You can determine your roof pitch without climbing on the roof using three different approaches, each matching one of this calculator’s input modes. For rise and run: use a level and tape measure in the attic. Hold a carpenter’s level against the underside of a rafter with the bubble centered. At the 12-inch mark, measure the vertical distance up to the rafter — that measurement in inches is the rise. Your pitch is rise/12. For the degree method: use a digital angle gauge or smartphone level app on the roof surface (or against a rafter in the attic) to read the exact slope angle. Enter that angle and the calculator converts it to rise/run notation. For the rafter-plus-span method: measure the actual sloped length of a rafter from the ridge board to the wall plate (excluding the tail overhang) and measure the horizontal half-span from the wall plate to directly below the ridge. Enter both values and the calculator uses the Pythagorean theorem to determine your exact pitch.

3 Real Roof Pitch Calculations

Example 1 — Standard Ranch Home, 5/12 Pitch, Charlotte, NC

Input: Rise = 5 in, Run = 12 in, Full span = 30 ft.

Angle: atan(5/12) = atan(0.4167) = 22.62 degrees.

Multiplier: sqrt(144+25)/12 = sqrt(169)/12 = 13/12 = 1.0833.

Rafter length (span/2 = 15 ft): 15 x 1.0833 = 16.25 ft.

Category: Moderate slope. Safe for DIY. All standard asphalt shingles and metal roofing approved.

Example 2 — From Digital Angle Gauge, 33.69 Degrees, Denver, CO

Input: Angle = 33.69 degrees, Span = 32 ft.

Rise per 12 in run: 12 x tan(33.69 deg) = 12 x 0.6667 = 8.00 in. Pitch: 8/12.

Multiplier: 1/cos(33.69 deg) = 1/0.8321 = 1.2019.

Rafter length (span/2 = 16 ft): 16 x 1.2019 = 19.23 ft.

Category: Steep slope. Professional installation recommended. All roofing materials compatible.

Example 3 — From Rafter and Span Measurement, Denver, CO

Input: Rafter length = 19.2 ft, Half-span = 16 ft.

Vertical rise: sqrt(19.2^2 – 16^2) = sqrt(368.64 – 256) = sqrt(112.64) = 10.61 ft.

Rise per 12 in run: (10.61/16) x 12 = 7.96 in. Pitch: approximately 8/12.

Multiplier: 19.2/16 = 1.200.

Useful for: When existing rafter lengths are known from a framing plan or measured directly in the attic, the rafter+span mode back-calculates the exact pitch, which can then be used as input for the shingle, metal, and underlayment calculators.

3 Expert Tips for US Roof Pitch

✅ Tip 1: Use the Pitch Multiplier from This Calculator in Your Shingle and Metal Roofing Material Orders

The single most valuable output from a roof pitch calculator is the pitch multiplier, which is the factor you apply to your horizontal house footprint area to get the actual sloped roof surface area you need to cover with roofing material. Without this conversion, a common and expensive mistake is to order shingles or metal panels based on the floor square footage of the house rather than the larger sloped surface. For a 5/12 pitch, the multiplier is 1.083: a 2,000-square-foot house footprint has a roof area of approximately 2,000 x 1.083 = 2,166 square feet. At a steeper 8/12 pitch, the same footprint produces 2,000 x 1.202 = 2,404 square feet of roof. The difference between using the multiplier correctly and forgetting it is approximately 4 to 5 squares of shingles on a typical US home, which at current material prices represents $700 to $2,000 in materials. Use the exact multiplier from this calculator as your conversion factor when using the roof shingle square calculator, the metal roofing calculator, and the roof underlayment calculator on this site.

📐 Tip 2: Measure Roof Pitch from Inside the Attic for Maximum Accuracy Without Climbing on the Roof

Many US homeowners are surprised to learn they can determine their roof pitch accurately without ever going on the roof. The attic provides direct access to the rafters, which carry the full pitch information. The professional method for measuring pitch from inside the attic: bring a 24-inch or 48-inch carpenter’s level, a tape measure, and a pencil. Hold the level against the underside of an accessible rafter with the bubble centered. Mark the 12-inch point on the level (measure 12 inches horizontally from the wall-side end of the level). At exactly that 12-inch point, measure straight up to the underside of the rafter. Record this vertical measurement in inches. This is your rise; your pitch is that number over 12. The 48-inch level gives you more stability than a shorter level when holding it against a rafter in a tight attic space. If the attic has blown-in insulation covering the floor joists, work carefully and step only on the framing members — falling through the ceiling drywall is the primary injury risk when working in US residential attics. A digital angle gauge (magnetic back or non-magnetic, available at US tool stores for $15 to $25) pressed directly against the rafter face gives an angle in degrees that this calculator converts instantly to pitch notation. The rafter surface gives the truest reading because it follows the actual roof plane; ceiling joists do not follow the pitch and cannot be used for this measurement.

🏠 Tip 3: Know the Minimum Pitch for Your Roofing Material Before Ordering

Roofing materials are not interchangeable across all pitches. Each material has a minimum slope requirement, and installing a material below its minimum pitch nearly guarantees water infiltration because gravity alone is insufficient to drain water off the roof before it finds a way through the roofing system at laps and fastener locations. US residential roofing minimum pitches by material: standard 3-tab asphalt shingles: 2/12 minimum with double underlayment and sealed laps (IRC requirement), 4/12 preferred for standard installation; architectural asphalt shingles: same 2/12 minimum, 4/12 preferred; standing seam metal: 1/12 minimum for snap-lock, 2/12 minimum for most floating-clip systems; corrugated or R-panel metal: 3/12 minimum per most US manufacturers; cedar shake and wood shingles: 3/12 minimum, 4/12 preferred; tile (concrete or clay): 2.5/12 minimum; slate: 4/12 minimum. Below 2/12, the roof is considered a low-slope or flat roof requiring EPDM membrane, TPO membrane, or modified bitumen rather than any of the above products. This calculator’s slope category output identifies which category your pitch falls in and flags any material compatibility limitations, giving you critical information before committing to a material purchase.

Frequently Asked Questions About Roof Pitch

What does 5/12 roof pitch mean?▼

A 5/12 roof pitch means the roof rises 5 inches vertically for every 12 inches of horizontal distance. In US roofing, pitch is always expressed as rise over run where the run is always 12 inches. A 5/12 pitch corresponds to an angle of 22.62 degrees and is the single most common residential roof pitch in the United States because it provides a comfortable balance between a traditional sloped appearance (not too flat, not too steep) and practical installation considerations (the slope is shallow enough for most DIY installers to work safely, and steep enough for all standard US roofing materials). A 5/12 pitch multiplier is 1.083, which means for every 100 square feet of horizontal floor area under the roof, the actual sloped roof surface is 108.3 square feet.

How do I convert roof pitch to degrees?▼

To convert any US roof pitch (rise/12) to degrees: use the inverse tangent function. Degrees = atan(rise/12) x (180/pi). For a 6/12 pitch: atan(6/12) = atan(0.5) = 26.57 degrees. For a 4/12 pitch: atan(4/12) = atan(0.333) = 18.43 degrees. For a 12/12 pitch: atan(12/12) = atan(1) = 45 degrees exactly. This calculator does this conversion automatically. The inverse is also useful: to find the pitch from a degree reading (such as from a digital angle gauge): rise = 12 x tan(degrees x pi/180). For 22.62 degrees: rise = 12 x tan(22.62) = 12 x 0.4167 = 5.0 inches, which is a 5/12 pitch. The degree measurement is more precise than the pitch notation because it can capture any slope angle, including non-standard pitches like 5.5/12 or 7.5/12 that do not have a simple fraction equivalent.

What is the pitch multiplier and how do I use it?▼

The pitch multiplier is the ratio of the sloped rafter length to the horizontal run. For a 5/12 pitch, the rafter over a 12-inch run is sqrt(144+25) = 13 inches, so the multiplier is 13/12 = 1.083. To use it: multiply your horizontal roof footprint area by the multiplier to get the actual sloped roof surface area. If your house is 30 x 52 feet with 12-inch overhangs, the horizontal adjusted footprint is 32 x 54 = 1,728 square feet. At a 5/12 pitch: 1,728 x 1.083 = 1,872 square feet of actual roof. Divide by 100 to get squares: 18.7 squares, rounded up to 19. This is the starting point for all roofing material orders: shingles (bundles = squares x 3 for 3-tab or x 4 for architectural), metal panels (panel count from coverage width and rafter length), and underlayment (rolls = squares divided by coverage per roll). The multiplier is also used to calculate rafter length from span: rafter length = half-span x multiplier. For a 32-foot-wide house with 12-inch overhangs: half-span = 17 feet. Rafter length = 17 x 1.083 = 18.4 feet. Order 18.5-foot panels.

What roof pitch is best for the US climate?▼

The best roof pitch for any US home depends primarily on the local climate and precipitation patterns. In the snowy northern United States (northern Midwest, New England, mountain states), steeper pitches of 6/12 to 9/12 are preferred because steeper slopes shed snow more quickly, reducing the structural load and ice dam risk. A 4/12 or 5/12 pitch in Minnesota or Vermont will hold more snow load than a 7/12 or 8/12 pitch on the same house. In the rainy Pacific Northwest, pitches of 5/12 to 8/12 are standard because the combination of steep slope and wide overhangs rapidly channels rain off the roof surface. In the dry Desert Southwest (Arizona, Nevada, southern California), lower pitches of 3/12 to 4/12 are more common because snow load and rapid rain runoff are not the primary design drivers, and low-slope construction is standard for commercial and residential flat-top buildings. In Florida and the Gulf Coast, roof pitch is heavily influenced by wind resistance requirements — pitches of 4/12 to 6/12 provide a good balance of wind uplift resistance and storm drainage. The IRC Wind Speed Map and local building codes in hurricane-prone US coastal areas specify minimum and maximum pitch ranges for certain roofing systems, with some high-wind zones requiring a minimum 2/12 pitch for metal roofing and enhanced fastening requirements at all pitches.

Is a 4/12 roof pitch OK for asphalt shingles?▼

Yes. A 4/12 pitch is fully compatible with all standard US asphalt shingles using standard installation methods. The IRC minimum pitch for asphalt shingles with standard double-layer starter course and normal underlayment is 4/12. Below 4/12 (at 2/12 to 3/12), asphalt shingles can still be used but require enhanced installation: double underlayment with both layers cemented together, sealed first course, and specified by the shingle manufacturer. Most US shingle manufacturers rate their standard products for 4/12 and above. For pitches of 2/12 to 4/12, verify your specific shingle brand’s approval for low-slope application. At 4/12, a 5/12, or 6/12 pitch, asphalt shingles perform identically to their rated specifications. The minimum pitch matters because at very low slopes, wind-driven rain can be pushed uphill under shingle laps, and water drainage slows enough that minor standing water can occur at low points. The 4/12 threshold provides enough slope that gravity drainage is reliable in essentially all normal US weather conditions.

How do I measure roof pitch without getting on the roof?▼

Three methods, all done safely from the ground or inside the building: From the attic: hold a 24-inch carpenter’s level against the underside of an accessible rafter. Center the bubble. At exactly the 12-inch mark (measured horizontally from one end of the level), measure straight up to the rafter with a tape measure. The measurement in inches is your rise, and your pitch is rise/12. From the ground (gable end view): look at the triangular gable end of the house. Use a smartphone level app or a digital protractor held at arm’s length against the slope visible on the gable. This gives you the slope angle in degrees, which you enter into this calculator’s degree mode. From inside the house: if you can see the roof slope from an upper-floor window or from the top of a ladder outside, a smartphone level app (using the phone’s accelerometer) pressed against a surface parallel to the roof slope can give you the angle directly. The smartphone method works best on 45-degree or steeper slopes where the slope is clearly visible and accessible from a window. The attic tape-measure method is the most accurate and most commonly used approach by US contractors when a client asks “what is my roof pitch.”

What is the steepest roof pitch I can safely walk on?▼

The generally accepted limit for walking on a roof without fall protection equipment is 6/12 (26.57 degrees) for an experienced worker with appropriate footwear. Below 6/12, most US roofing workers and experienced DIYers can move on the roof surface without mechanical assistance in dry conditions. At 6/12 and steeper, the angle is enough that dry rubber-soled shoes begin to slip on smooth asphalt shingles, especially in direct sun where the asphalt softens slightly. OSHA standards for roofing work require fall protection (harness and anchor, safety nets, or guardrail systems) for workers on slopes of 4/12 and above when working at heights greater than 6 feet. For homeowner DIY projects: most roofing professionals recommend hiring a contractor for any roof steeper than 6/12, and strongly advise against DIY work on roofs steeper than 8/12 (33.7 degrees). At 9/12 and above, the slope is steep enough that sliding even a few feet on the surface can put the worker at the roof edge with no time to arrest the fall. If you must work on a steep slope roof, a properly anchored roof bracket system (roof jacks and planks) is the standard US safety approach, combined with a full harness attached to a ridge anchor.

Related Roofing Calculators

Editorial Standards and Legal Disclaimer

Rise/Run mode: angle_deg = atan(rise/run) x (180/pi). Multiplier = sqrt(run^2 + rise^2) / run. Rafter length = (span/2) x multiplier. Degree mode: rise = run x tan(angle_deg x pi/180). Multiplier = 1/cos(angle_deg x pi/180). Rafter+Span mode: vertical_rise = sqrt(rafter^2 – half_span^2). Rise per 12 = (vertical_rise/half_span) x 12. Multiplier = rafter/half_span. All trigonometric functions use standard JavaScript Math library. Pitch multiplier rounded to 4 decimal places for display; full precision used in all calculations. Slope categories: very low (below 2/12), low (2-4/12), moderate (4-7/12), steep (7-10/12), very steep (10/12+). Roofing material compatibility based on most common US manufacturer specifications; always verify with your specific product’s installation instructions. DIY safety ratings are general guidelines; OSHA 1926.502 requires fall protection for roofing workers at 4/12 and above. Last reviewed: August 2026.