# Roof Pitch Calculator Calculate roof pitch from rise and run. Convert between degrees, percentage, radians, and x:12 ratio instantly. Canonical page: https://invoicemama.com/calculators/roof-pitch-calculator This is a free browser calculator. Treat results as planning aids and confirm figures against your own measurements, codes, and professional judgment. ## How to use this roof pitch calculator Enter rise and run (or another pitch format) to convert roof pitch to degrees, radians, percentage, and common x:12 ratios, and to see related measurements for planning rafters and materials. ### 1. Choose your input method Enter vertical rise and horizontal run in inches or feet, or type a pitch ratio such as 6:12. Pick the units that match how you measured on site or read from plans. ### 2. Enter your measurements Fill in rise and run consistently (same unit system). For existing roofs, measure along the roof plane or use plan dimensions your engineer or designer provided. ### 3. Read converted pitch values Review pitch in degrees, radians, percent slope, and ratio form. Use these values for truss ordering, cutting angles, and comparing to manufacturer tables. ### 4. Use related outputs for layout Check rafter length factors or multipliers shown for estimating lumber and coverage. Always verify critical angles and spans against local code and structural drawings. ## Frequently asked questions ### What is roof pitch and how is it measured? Roof pitch is the steepness or angle of a roof, expressed as a ratio of vertical rise to horizontal run. The standard format is X:12, meaning X inches of rise for every 12 inches of horizontal run. For example, a 6:12 pitch rises 6 inches for every 12 inches of run, equivalent to a 26.57° angle or 50% grade. ### How to calculate roof pitch in degrees? To calculate roof pitch in degrees: 1) Measure the vertical rise (height) and horizontal run (distance). 2) Divide rise by run to get the ratio. 3) Calculate the arctangent (inverse tangent) of this ratio. 4) Convert from radians to degrees by multiplying by 180/π. Example: 6-inch rise over 12-inch run = 6/12 = 0.5, then arctan(0.5) = 26.57°. Our calculator performs all these steps instantly when you enter your measurements. ### How do I convert roof pitch to degrees? To convert roof pitch to degrees, use the formula: degrees = arctan(rise/run) x (180/π). For a 6:12 pitch: arctan(6/12) = arctan(0.5) = 26.57°. Our calculator does this conversion instantly, showing pitch in degrees, radians, percentage, and ratio format. ### What is a 4/12 roof pitch in degrees? A 4/12 roof pitch equals 18.43 degrees. This is considered a standard residential pitch, providing adequate water runoff while remaining walkable for maintenance. It's one of the most common pitches for homes in North America. ### What roof pitch is considered walkable? Roofs with a pitch of 6:12 (26.57°) or less are generally considered walkable without special equipment. Pitches from 7:12 to 9:12 require caution and possibly roof jacks. Above 10:12 (39.81°), fall protection is mandatory. A 12:12 pitch (45°) is extremely steep and requires specialized safety equipment. ### What is the roof pitch multiplier and how do I use it? The roof pitch multiplier (or factor) converts horizontal floor area to actual sloped roof area. It's calculated as √(1 + (rise/run)²). For a 6:12 pitch, the multiplier is 1.118, meaning a 1,000 sq ft floor area equals 1,118 sq ft of actual roof surface. This is essential for accurate material estimates. ### How do I calculate rafter length from roof pitch? Rafter length = Run x √(1 + (rise/run)²), or simply Run x Rafter Factor. For a 6:12 pitch with a 12-foot run: 12 x 1.118 = 13.42 feet rafter length. Our calculator shows the rafter-per-run factor, which you multiply by your actual run distance to get rafter length. ### What is the standard roof pitch for residential homes? The most common residential roof pitches in the US range from 4:12 to 6:12 (18.43° to 26.57°). A 4:12 pitch is considered the minimum for standard asphalt shingles. Areas with heavy snowfall often use steeper pitches (8:12 to 12:12) to shed snow, while modern architecture may use lower slopes with specialized roofing materials. ### How does roof pitch affect material costs? Steeper roofs require more materials due to increased surface area. A 12:12 pitch (45°) has 41% more roof area than a flat roof covering the same floor space. Additionally, steeper roofs cost more to install due to safety equipment requirements and slower work pace. Always use the pitch multiplier when estimating materials. ### What is the minimum roof pitch for shingles? The minimum recommended pitch for standard asphalt shingles is 4:12 (18.43°). Some manufacturers allow 2:12 to 4:12 with special underlayment and application methods. Below 2:12, you need specialized low-slope roofing materials like modified bitumen, EPDM, or TPO membrane systems. ### How do I measure roof pitch without going on the roof? You can measure roof pitch from the attic: place a level horizontally against a rafter, measure 12 inches from one end, then measure the vertical distance from that point to the rafter. Alternatively, use a smartphone inclinometer app from the ground to estimate the angle, or measure from inside through a gable window. ### What is the best pitch for a shed roof? The best pitch for a shed roof depends on your climate and roofing material. Most sheds use a 3:12 to 4:12 pitch (14° to 18°), which provides adequate drainage while keeping construction simple. In heavy snow areas, consider 4:12 or steeper. For metal roofing, you can go as low as 1:12 with proper sealing. Our calculator works perfectly for shed roof calculations. ### How do I calculate pitch for a lean-to roof? A lean-to (or mono-pitch) roof has a single slope. Measure the vertical rise from the low wall to the high wall, and the horizontal run (distance between walls). Enter these values in our calculator to get the pitch. Common lean-to pitches range from 2:12 to 6:12 depending on the roofing material and local building codes. ### Is there a roof pitch calculator app? While there are dedicated apps, our web-based roof pitch calculator works on any smartphone, tablet, or computer without downloading anything. Simply open this page in your mobile browser, enter your measurements, and get instant results. It works offline once loaded and is always free to use. ### What pitch should I use for a porch roof? Porch roofs (often lean-to style) typically use a 2:12 to 4:12 pitch. The pitch should be steep enough for water drainage but low enough to maintain headroom. A 3:12 pitch is a popular choice, providing good drainage while keeping the structure visually proportional. Match or complement the pitch of your main roof when possible. ## Roofing Contractors: Get Paid Faster Invoice Mama helps roofing contractors create professional estimates and invoices in seconds. Turn your calculations into polished documents that get you paid faster. - [Create your first invoice free](https://app.invoicemama.com/sign-up) --- Invoice Mama is invoicing software for contractors, freelancers, and small businesses. It is not a tax, legal, or accounting firm. For current pricing, use the live pricing page. **More:** [Home](https://invoicemama.com/) - [Pricing](https://invoicemama.com/pricing) - [Guides](https://invoicemama.com/guides) - [Tools](https://invoicemama.com/tools) - [Calculators hub](https://invoicemama.com/calculators)