Roof Pitch Calculator
Calculate roof pitch from rise and run. Convert between degrees, percentage, radians, and x:12 ratio instantly.
Calculate roof pitch instantly from rise and run measurements. Convert between degrees, radians, percentage grade, and standard x:12 ratio. Get rafter length factor and roof area multiplier for accurate material estimates.
Whether you're a contractor estimating materials, a homeowner planning a project, or a student learning construction math, this free roof pitch calculator provides instant, accurate conversions. Enter your rise and run in any unit (inches, feet, meters, or centimeters) and get complete pitch data including the all-important roof area multiplier.
Understanding Roof Pitch: The Complete Guide
Roof pitch is fundamental to roofing calculations. Here's everything you need to know.
Roof pitch describes how steep a roof is. It's the ratio of vertical rise to horizontal run, typically expressed as "X:12" in North America. A 6:12 pitch means the roof rises 6 inches for every 12 inches of horizontal distance.
The same pitch can be expressed multiple ways: as a ratio (6:12), angle in degrees (26.57°), angle in radians (0.4636), or percentage grade (50%). Our calculator converts between all formats instantly.
- Flat to Low Slope (0:12 to 3:12)0° to 14° - Requires membrane roofing systems. Water drains slowly; needs enhanced waterproofing.
- Conventional Pitch (4:12 to 9:12)18° to 37° - Standard for most homes. Supports shingles, tiles, and metal roofing.
- Steep Slope (10:12 to 12:12)40° to 45° - Excellent drainage, dramatic appearance. Requires safety equipment for installation.
- Very Steep (Over 12:12)45°+ - Specialty roofs like A-frames. Maximum drainage but challenging installation.
Visual Roof Pitch Comparison
See how different pitches compare at a glance
This interactive chart shows all common roof pitches from nearly flat (1:12) to steep (12:12). Each bar represents the angle in degrees, with the roof line illustration showing the actual slope.
Roof Pitch Calculation Example: Step-by-Step
Follow along with real numbers to understand how pitch calculations work
Let's calculate the roof pitch for a garage with a 6-foot rise over a 12-foot horizontal run. We'll find the pitch ratio, angle in degrees, percentage grade, and rafter length.
- 1
Step 1: Calculate the Pitch Ratio
Divide rise by run: 6 ÷ 12 = 0.5. This means the roof rises 0.5 feet for every 1 foot of horizontal distance. In standard notation, this is a 6:12 pitch.
- 2
Step 2: Convert to Degrees
Use arctangent: angle = arctan(6/12) = arctan(0.5) = 26.57°. This is the actual angle of the roof slope measured from horizontal.
- 3
Step 3: Calculate Percentage Grade
Multiply ratio by 100: 0.5 × 100 = 50%. A 6:12 pitch equals a 50% grade, meaning the roof rises 50 feet for every 100 feet of horizontal distance.
- 4
Step 4: Find the Rafter Factor (Multiplier)
Use Pythagorean theorem: √(1 + 0.5²) = √(1 + 0.25) = √1.25 = 1.118. This multiplier converts horizontal measurements to actual roof surface measurements.
- 5
Step 5: Calculate Rafter Length
Multiply run by rafter factor: 12 ft × 1.118 = 13.42 feet. This is the length of the rafter from the wall plate to the ridge (before adding overhang).
Summary: 6-foot Rise / 12-foot Run
• Pitch: 6:12 (or 6/12) • Angle: 26.57° • Radians: 0.4636 rad • Grade: 50% • Rafter Factor: 1.118 • Rafter Length: 13.42 ft (for 12 ft run)
Pro tip: Don't forget to add overhang length to your rafter calculation. For a 12-inch overhang at 6:12 pitch, add 12" × 1.118 = 13.4 inches to the rafter length.
Roof Pitch Formulas Explained
The mathematical relationships behind pitch calculations
All roof pitch calculations derive from basic trigonometry. Understanding these formulas helps you verify calculations and solve related problems:
Calculation | Formula | Example (6:12 Pitch) |
|---|---|---|
| Pitch Ratio | Rise ÷ Run | 6 ÷ 12 = 0.5 |
| Degrees | arctan(Rise/Run) × (180/π) | arctan(0.5) = 26.565° |
| Radians | arctan(Rise/Run) | arctan(0.5) = 0.4636 rad |
| Percentage | (Rise/Run) × 100 | 0.5 × 100 = 50% |
| Rafter Factor | √(1 + (Rise/Run)²) | √(1 + 0.25) = 1.118 |
| Rafter Length | Run × Rafter Factor | 12ft × 1.118 = 13.42ft |
The rafter factor (also called pitch multiplier) is particularly important for estimating materials. It tells you how much longer the actual roof surface is compared to the horizontal distance.
Complete Roof Pitch Multiplier Table
The essential reference for calculating roof area and rafter lengths
This table is your go-to reference for roof pitch calculations. The multiplier (also called slope correction factor or rafter factor) converts horizontal measurements to actual sloped roof measurements. Bookmark this page for quick access on the job site.
Pitch | Degrees | Radians | Grade % | Multiplier | Category |
|---|---|---|---|---|---|
| 1:12 | 4.76° | 0.0831 | 8.33% | 1.003 | Nearly Flat |
| 2:12 | 9.46° | 0.1651 | 16.67% | 1.014 | Low Slope |
| 3:12 | 14.04° | 0.2450 | 25.00% | 1.031 | Low Slope |
| 4:12 | 18.43° | 0.3217 | 33.33% | 1.054 | Standard |
| 5:12 | 22.62° | 0.3948 | 41.67% | 1.083 | Standard |
| 6:12 | 26.57° | 0.4636 | 50.00% | 1.118 | Standard |
| 7:12 | 30.26° | 0.5281 | 58.33% | 1.158 | Moderate |
| 8:12 | 33.69° | 0.5880 | 66.67% | 1.202 | Steep |
| 9:12 | 36.87° | 0.6435 | 75.00% | 1.250 | Steep |
| 10:12 | 39.81° | 0.6947 | 83.33% | 1.302 | Very Steep |
| 11:12 | 42.51° | 0.7419 | 91.67% | 1.357 | Very Steep |
| 12:12 | 45.00° | 0.7854 | 100.00% | 1.414 | Extreme (45°) |
How to use: Multiply your horizontal floor area by the multiplier to get actual roof area. Example: 2,000 sq ft floor × 1.118 (6:12 pitch) = 2,236 sq ft roof surface.
Shed Roof Pitch Calculator
Calculate the perfect pitch for your shed, workshop, or outbuilding
Building a shed? Getting the roof pitch right is essential for proper drainage and choosing the right roofing materials. Our calculator works perfectly for shed roofs, whether you're building a small garden shed or a large workshop.
Most sheds use a single-slope (mono-pitch) or gable roof design. The pitch you choose affects material costs, headroom, and how well the roof sheds water and snow.
- 1:12 to 2:12 (Low Slope)Best for: Metal roofing with sealant. Minimal headroom loss. Requires waterproof membrane underlayment.
- 3:12 to 4:12 (Standard Shed)Best for: Most shed projects. Works with metal panels, asphalt shingles (with underlayment), and rolled roofing.
- 5:12 to 6:12 (Steeper Shed)Best for: Snow country or matching house roof pitch. More material needed but excellent drainage.
Pro tip: For a 10-foot wide shed with a single-slope roof, a 3:12 pitch means the high side is 2.5 feet taller than the low side (10 × 3/12 = 2.5 ft rise).
Lean-To Roof Pitch Calculator
Calculate pitch for porch roofs, additions, and mono-slope structures
A lean-to roof (also called a shed roof, mono-pitch, or pent roof) has a single sloping surface that leans against an existing wall or structure. This design is popular for porches, carports, additions, and covered patios.
To calculate lean-to roof pitch, you need two measurements: the rise (vertical height difference between the low and high ends) and the run (horizontal distance from the supporting wall to the outer edge).
- 1
Measure the Rise
The rise is the vertical distance from where the lean-to connects to the main structure down to the top of the low wall or support posts.
- 2
Measure the Run
The run is the horizontal distance from the main wall to the outer edge of the lean-to roof (not including overhang).
- 3
Enter Values Above
Input your rise and run measurements in our calculator. For a 6-foot run with 18-inch rise, you'd get a 3:12 pitch.
Lean-To Type | Recommended Pitch | Notes |
|---|---|---|
| Porch/Patio Cover | 2:12 to 4:12 | Balance between headroom and drainage |
| Carport | 1:12 to 3:12 | Low pitch for vehicle clearance |
| Home Addition | 3:12 to 6:12 | Match existing roof pitch when possible |
| Firewood Shelter | 2:12 to 3:12 | Simple construction, basic drainage |
| Greenhouse Lean-To | 4:12 to 6:12 | Steeper for snow shedding and light entry |
Roof Pitch Calculator App: Use It on Any Device
No download required. Works on your phone, tablet, or computer.
Looking for a roof pitch calculator app? You've already found the best solution. Our web-based calculator works on any device with a browser. No app store, no downloads, no storage space needed.
- Works on iPhone & AndroidOpen this page in Safari, Chrome, or any mobile browser. The calculator is fully responsive and touch-friendly.
- No App Download NeededSkip the app store entirely. Bookmark this page for instant access on the job site.
- Always Up to DateUnlike apps that need updates, our web calculator is always the latest version.
- Works Offline TooOnce loaded, the calculator works even without internet. Perfect for remote job sites.
Roofing contractors love using this calculator on-site. Pull out your phone, enter the rise and run you just measured, and get instant pitch data. Copy results with one tap to paste into your estimate.
Rafter Length Calculator: From Pitch to Cutting Length
Calculate exact rafter lengths for framing
Once you know your roof pitch, calculating rafter length is straightforward. Our calculator gives you the rafter factor, which you multiply by your run to get the rafter length.
Pitch | Rafter Factor | 10 ft Run | 12 ft Run | 14 ft Run |
|---|---|---|---|---|
| 3:12 | 1.031 | 10.31 ft | 12.37 ft | 14.43 ft |
| 4:12 | 1.054 | 10.54 ft | 12.65 ft | 14.76 ft |
| 5:12 | 1.083 | 10.83 ft | 13.00 ft | 15.16 ft |
| 6:12 | 1.118 | 11.18 ft | 13.42 ft | 15.65 ft |
| 8:12 | 1.202 | 12.02 ft | 14.42 ft | 16.83 ft |
| 10:12 | 1.302 | 13.02 ft | 15.62 ft | 18.23 ft |
| 12:12 | 1.414 | 14.14 ft | 16.97 ft | 19.80 ft |
Important: These are theoretical rafter lengths. For actual cutting length, you'll need to:
- Add OverhangCalculate overhang separately using the same rafter factor. 12" overhang at 6:12 pitch = 12 × 1.118 = 13.4" rafter extension.
- Subtract Ridge DeductionDeduct half the ridge board thickness from the run before calculating. For 1.5" ridge board, deduct 0.75" from run.
- Account for BirdsmouthThe birdsmouth cut (seat cut) affects where the rafter sits on the wall plate. Measure from the building line.
How to Measure Roof Pitch: 4 Methods
Different techniques for different situations
- 1
From the Attic (Most Accurate)
Place a 24" level against a rafter. At the 12" mark, measure the vertical distance to the rafter. This measurement is your rise per 12" run. Example: 6" measurement = 6:12 pitch.
- 2
On the Roof (Direct Measurement)
Use a pitch finder tool or place a level on the roof surface. Measure 12" horizontally, then measure the vertical drop from level to roof. Requires roof access and safety precautions.
- 3
Smartphone App (Easiest)
Use an inclinometer app - most phones have one built in. Place your phone flat on the roof surface and read the angle directly in degrees. Convert to ratio using our calculator.
- 4
From the Ground (Estimation)
Photograph the roof profile and use geometry apps to calculate the angle. Less accurate but useful for initial estimates when roof access isn't possible.
Calculating Rafter Length from Pitch
How the rafter factor simplifies construction math
The rafter factor (shown as "Rafter/Run" in our calculator) tells you how long a rafter is compared to the horizontal run. This is essential for cutting rafters to the correct length.
Example: For a roof with 6:12 pitch and 14-foot run (from wall to ridge): Rafter Factor = 1.118 Rafter Length = 14 × 1.118 = 15.65 feet Remember to add for overhangs and adjust for ridge board thickness.
Using the Roof Area Multiplier
Why floor area isn't the same as roof area
A common mistake is assuming a 1,500 sq ft house needs 1,500 sq ft of roofing material. The actual roof surface area is always larger than the floor area (unless the roof is perfectly flat) because the roof slopes upward.
The area multiplier (same as rafter factor) converts floor area to actual roof area:
Pitch | Multiplier | 1,500 sq ft Floor = | Extra Material |
|---|---|---|---|
| 4:12 | 1.054 | 1,581 sq ft roof | +5.4% |
| 6:12 | 1.118 | 1,677 sq ft roof | +11.8% |
| 8:12 | 1.202 | 1,803 sq ft roof | +20.2% |
| 10:12 | 1.302 | 1,953 sq ft roof | +30.2% |
| 12:12 | 1.414 | 2,121 sq ft roof | +41.4% |
Always add 10-15% waste factor on top of the calculated roof area for cuts, overlaps, and installation waste.
Minimum Pitch Requirements by Roofing Material
Not all materials work on all pitches
- Built-Up Roofing (BUR)Minimum 0.25:12 (1/4" per foot). Flat roof systems.
- EPDM/TPO MembraneMinimum 0.25:12. Ideal for low-slope commercial roofs.
- Modified BitumenMinimum 0.5:12 to 2:12. Low-slope residential option.
- Asphalt ShinglesMinimum 4:12 standard, 2:12 with enhanced underlayment. Most common residential.
- Wood Shingles/ShakesMinimum 3:12 with solid sheathing, 4:12 with spaced sheathing.
- Clay/Concrete TilesMinimum 4:12. Heavy; requires strong framing.
- Metal PanelsMinimum 3:12 for exposed fastener, 1:12 for standing seam with sealant.
- SlateMinimum 4:12. Premium material, very long-lasting.
How to Use This Roof Pitch Calculator
Get accurate results in seconds
- 1
Select Your Unit System
Choose between inches (most common for US construction), feet, meters, or centimeters. The calculator converts values automatically when you switch units.
- 2
Enter Rise and Run
Input the vertical rise and horizontal run measurements. For standard pitch notation, use 12 as the run (e.g., rise=6, run=12 for 6:12 pitch). Or use actual measurements from your roof.
- 3
Read Your Results
Instantly see pitch in degrees, radians, percentage, and x:12 ratio. The rafter factor and area multiplier help with material calculations. Click any result to copy it.
Common Roof Pitch Conversions
Quick reference for the most searched pitch values
3/12 Pitch = 14.04°
Low slope. 25% grade. Multiplier: 1.031. Minimum for metal roofing. Easy to walk on.
4/12 Pitch = 18.43°
Standard residential minimum. 33.33% grade. Multiplier: 1.054. Walkable without equipment.
5/12 Pitch = 22.62°
Common residential pitch. 41.67% grade. Multiplier: 1.083. Comfortable to walk on.
6/12 Pitch = 26.57°
Most popular residential pitch. 50% grade. Multiplier: 1.118. Walkable with caution.
8/12 Pitch = 33.69°
Steep residential. 66.67% grade. Multiplier: 1.202. Requires roof brackets for safety.
12/12 Pitch = 45°
Very steep slope. 100% grade. Multiplier: 1.414. Full safety equipment required.
Roof Pitch Calculator for Contractors
Estimate materials and labor accurately
As a roofing contractor, accurate pitch calculations directly impact your bottom line. Underestimate materials and you're making extra trips to the supplier. Overestimate and you're eating the cost of excess inventory.
- Material TakeoffsUse the roof area multiplier to convert floor area to actual roof area. A 2,000 sq ft footprint at 6:12 pitch = 2,236 sq ft of roofing (2,000 × 1.118).
- Labor EstimatesSteeper pitches require more time and safety equipment. Factor in reduced productivity above 8:12 pitch and mandatory fall protection above 4:12.
- Waste FactorsAdd 10% waste for simple roofs, 15% for complex roofs with valleys and hips. Steeper pitches may require additional waste allowance.
- Pricing AdjustmentsMany contractors add 10-20% to labor costs for each step above 6:12 pitch due to slower work pace and safety requirements.
Quick estimate example: 1,800 sq ft house, 6:12 pitch, standard shingles. Roof area = 1,800 × 1.118 = 2,012 sq ft. Add 15% waste = 2,314 sq ft. At 100 sq ft per bundle = 24 bundles (8 squares) needed.
Roof Pitch by Climate: Regional Recommendations
How weather affects your pitch choice
Your local climate plays a major role in determining the ideal roof pitch. What works in Arizona won't work in Minnesota. Here's how to match pitch to your weather conditions:
Climate | Recommended Pitch | Reason |
|---|---|---|
| Heavy Snow (MN, MI, CO) | 6:12 to 12:12 | Steeper pitch sheds snow before weight accumulates |
| Heavy Rain (FL, LA, WA) | 4:12 to 8:12 | Good drainage prevents ponding and leaks |
| Hurricane Zone (FL, TX Coast) | 6:12 or less | Lower pitch reduces wind uplift |
| Hot & Dry (AZ, NV) | 2:12 to 4:12 | Low slope adequate, reduces material costs |
| Mixed Climate (Most US) | 4:12 to 6:12 | Balanced approach for varied conditions |
Always check local building codes. Many jurisdictions have minimum pitch requirements based on historical weather data and material specifications.
Roof Pitch by Roof Type
Typical pitch ranges for different roof styles
Different roof styles have characteristic pitch ranges. Understanding these helps you match your calculations to your specific project type.
- Gable RoofPitch range: 4:12 to 12:12. The classic triangular roof with two sloping sides meeting at a ridge. Most common in residential construction. Works with virtually all roofing materials.
- Hip RoofPitch range: 4:12 to 8:12. All four sides slope downward to the walls. More stable in high winds than gable roofs. The same pitch is typically used on all sides.
- Gambrel Roof (Barn Style)Upper pitch: 4:12 to 6:12. Lower pitch: 12:12 to 20:12. The classic barn roof with two different slopes on each side. Lower section is much steeper for maximum headroom.
- Mansard RoofUpper pitch: Nearly flat (1:12 to 2:12). Lower pitch: Very steep (20:12+). French-inspired design with four sides. Lower slopes are almost vertical for maximum living space.
- Shed/Mono-Pitch RoofPitch range: 1:12 to 6:12. Single sloped surface. Popular for modern homes, additions, porches, and outbuildings. Simple construction with one direction of water flow.
- Flat RoofPitch range: 0.25:12 to 2:12. Not truly flat, requires slight slope for drainage. Common in commercial buildings and modern residential. Requires membrane roofing systems.
When calculating pitch for complex roofs with multiple sections (like gambrel or mansard), calculate each section separately. Our calculator works for any individual roof plane.
Roofing Cost Estimates by Material
Approximate costs to help with project budgeting
Roofing costs vary significantly by material, region, and roof complexity. These estimates include materials and professional installation for a typical residential roof. Use the pitch multiplier to calculate your actual roof area before estimating costs.
Material | Cost per Sq Ft | Lifespan | Best For |
|---|---|---|---|
| Asphalt Shingles (3-Tab) | $3.50 - $5.50 | 15-20 years | Budget-friendly projects |
| Architectural Shingles | $4.50 - $7.00 | 25-30 years | Most residential homes |
| Metal Roofing (Standing Seam) | $8.00 - $14.00 | 40-70 years | Long-term value, modern look |
| Metal Panels (Exposed Fastener) | $5.00 - $9.00 | 25-40 years | Sheds, barns, budget metal |
| Clay/Concrete Tiles | $10.00 - $18.00 | 50-100 years | Southwest, Mediterranean style |
| Slate | $15.00 - $30.00 | 75-150 years | Historic homes, premium finish |
| Wood Shakes | $8.00 - $14.00 | 25-30 years | Rustic, natural appearance |
| TPO/EPDM (Flat Roof) | $5.00 - $10.00 | 20-30 years | Low-slope commercial/residential |
Example Cost Calculation
For a 1,500 sq ft home with 6:12 pitch using architectural shingles: 1. Floor area: 1,500 sq ft 2. Apply multiplier: 1,500 × 1.118 = 1,677 sq ft roof area 3. Add 15% waste: 1,677 × 1.15 = 1,929 sq ft materials needed 4. Cost range: 1,929 × $4.50 to $7.00 = $8,680 to $13,500
Note: Costs vary significantly by region, contractor, roof complexity, and market conditions. Steeper pitches (above 6:12) typically add 10-25% to labor costs due to safety requirements. Get multiple quotes for accurate pricing in your area.
Roof Pitch for Snow: Cold Climate Recommendations
Prevent snow accumulation and ice dams with the right pitch
In areas with heavy snowfall, roof pitch is critical for safety and longevity. Snow loads can exceed 30-40 pounds per square foot, stressing roof structures. The right pitch helps snow slide off before dangerous accumulation.
- Heavy Snow Areas: 6:12 Minimum (30°+)Regions like Minnesota, Michigan, and Colorado mountains should use 6:12 or steeper. Snow slides off before accumulating to dangerous weights.
- Ice Dam Prevention: 4:12+ with Proper InsulationIce dams form when heat escapes through the roof. Adequate pitch combined with proper attic insulation and ventilation prevents ice buildup at eaves.
- Metal Roofing AdvantageMetal roofs shed snow more readily than shingles due to their smooth surface. In snow country, metal roofing at 3:12+ often performs better than shingles at 6:12.
- Snow Guards for Steep PitchesVery steep roofs (8:12+) may need snow guards to prevent avalanche-style snow slides that can damage gutters, landscaping, or people below.
Local building codes in snow-prone areas often specify minimum roof pitches and snow load requirements. Always verify with your local building department before finalizing roof design.
Frequently Asked Questions
Detailed answers to common roof pitch 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) × (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 × √(1 + (rise/run)²), or simply Run × Rafter Factor. For a 6:12 pitch with a 12-foot run: 12 × 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.
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Start Calculating Your Roof Pitch
Accurate measurements lead to successful projects
Whether you're ordering materials, cutting rafters, or just curious about your roof's angle, this calculator gives you all the numbers you need. Enter your rise and run above to get instant results in every format: degrees, radians, percentage, ratio, and the crucial roof area multiplier.
For roofing contractors: Once you've calculated your pitch and materials, Invoice Mama helps you create professional estimates and invoices in seconds. Turn accurate calculations into polished documents that get you 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.