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Choose a Calculation Method
Select Rise & Run, Pitch Ratio or Angle depending on the measurements you already know.
Free Roofing Calculator
Roof Pitch Calculator
Calculate roof pitch, roof angle, slope percentage, rafter length and pitch factor instantly using rise and run, pitch ratio or roof angle.
in
in
: 12
in
°
in
Roof Pitch
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Angle
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Slope
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Rafter Length
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Pitch Factor
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Enter your roof measurements and calculate instantly.
What Is Roof Pitch?
Roof pitch describes how steep a roof is. In the United States and Canada, roof pitch is commonly written as a ratio such as 4:12, 6:12 or 8:12. The first number represents the vertical rise of the roof for every 12 units of horizontal run.
For example, a 6:12 roof pitch rises 6 inches for every 12 inches it runs horizontally. That same roof has an angle of approximately 26.57 degrees and a slope of 50%.
This calculator converts between roof pitch ratio, angle and slope while also calculating approximate rafter length and pitch factor. You can work in inches, feet, centimeters or meters.
Example Calculation
Rise
6 in
Run
12 in
Roof Pitch
6 : 12
26.57° • 50% slope
How to Use the Roof Pitch Calculator
Get your roof measurements and calculate pitch in three simple steps.
02
Enter Your Measurements
Enter the roof rise and horizontal run, or enter an existing pitch ratio or angle. Choose your preferred measurement unit.
03
Get Instant Results
The calculator returns pitch ratio, roof angle, slope percentage, rafter length and pitch factor immediately.
Roof Pitch to Degrees Chart
Use this quick reference chart to compare common roof pitch ratios, roof angles and slope percentages.
View the full Roof Pitch to Degrees guide →How to Calculate Roof Pitch
Roof pitch is based on the relationship between vertical rise and horizontal run.
Roof Pitch Formula
Divide the vertical rise by the horizontal run.
Rise ÷ Run
When the run is normalized to 12 units, the result is normally shown as a pitch ratio such as 4:12 or 6:12.
Roof Slope Percentage
(Rise ÷ Run) × 100
Roof Angle
Angle = arctan(Rise ÷ Run)
Common Roof Pitch Examples
These are several commonly referenced roof pitch ratios and their approximate angles.
Roof Pitch vs Roof Slope
Pitch ratio and slope percentage describe the same roof incline in different formats.
Roof Pitch
6 : 12A 6:12 roof rises 6 units vertically for every 12 units of horizontal run.
Roof Slope
50%The same 6:12 roof has a slope percentage of 50% and an approximate roof angle of 26.57°.
Roofing Tools & Guides
Go beyond pitch conversion with dedicated calculators for roof geometry and material estimating, plus practical measurement, material and methodology guides.
Calculators & Converters
Use the tool that matches the measurement or estimate you need.
Framing Tool
Rafter Length Calculator
Calculate common rafter length from roof pitch and building span or run, with optional horizontal overhang.
Calculate rafter length → Area Tool Roof Area CalculatorEstimate sloped roof square footage from building size, pitch, overhang and an optional waste allowance.
Calculate roof area → Vertical Geometry Roof Rise CalculatorFind rise to ridge from pitch and building span or run, with optional wall height for total ridge height.
Calculate roof rise → Material Estimate Roofing Squares CalculatorConvert roof square footage into roofing squares, apply waste and estimate bundles using product-specific coverage.
Calculate roofing squares → Multiplier Guide Roof Pitch FactorFind the pitch multiplier used to convert horizontal measurements into sloped roof measurements.
View pitch factors → Conversion Guide Roof Pitch to DegreesConvert common roof pitch ratios into roof angles and slope percentages using the full reference chart.
Convert pitch to degrees →
Practical Roofing Guides
Understand the measurements, assumptions and real-world context behind the numbers.
Measurement Guide
How to Measure Roof Pitch
Compare safer measurement methods using an accessible attic, known rise and run, a visible gable or a reliable angle reading.
Learn how to measure pitch → Material Guide Roof Pitch by Roofing MaterialCompare slope considerations for asphalt shingles, metal, tile, cedar and low-slope roofing systems.
Compare roofing materials → Workflow Guide Gable Roof Measurement GuideFollow span, run and pitch through roof rise, rafter length, roof surface area and roofing squares in one worked example.
Follow the gable workflow → Methodology How Our Calculators WorkReview the formulas, assumptions, validation examples and limitations behind the site's roofing calculators.
View formulas & methodology →Roof Pitch Calculator FAQs
Quick answers to common roof pitch, slope and angle questions.
What is a 4:12 roof pitch in degrees?
A 4:12 roof pitch has an angle of approximately
18.43 degrees and a slope of about
33.33%.
What angle is a 6:12 roof pitch?
A 6:12 roof pitch is approximately
26.57 degrees. It represents a 50% slope.
What is an 8:12 roof pitch in degrees?
An 8:12 roof pitch is approximately
33.69 degrees with a slope of about
66.67%.
Is a 12:12 roof pitch a 45-degree roof?
Yes. A 12:12 pitch rises the same amount as it runs
horizontally, creating a 45-degree angle
and a 100% slope.
How do I calculate roof pitch from rise and run?
Divide the rise by the run. If you want the conventional
X:12 roof pitch format, normalize the run to 12 units.
For example, 6 inches of rise over 12 inches of run equals
a 6:12 pitch.
Can I calculate roof pitch using feet?
Yes. As long as rise and run use the same measurement unit,
the ratio remains valid. This calculator supports feet,
inches, centimeters and meters.
What is roof pitch factor?
Pitch factor is the multiplier between horizontal run
and sloped roof length. It can be useful when estimating
approximate rafter or roof surface measurements.
How is rafter length calculated?
For a simple right-triangle roof section, rafter length
can be calculated using the Pythagorean relationship between
rise and run. Real roofs may require additional adjustments
for overhangs, ridge details and construction conditions.
What is considered a steep roof pitch?
Roof terminology varies by roofing system and local practice,
but as pitch increases the roof becomes progressively steeper.
Always follow the roofing manufacturer's requirements and
applicable local building standards for a real project.
Calculate Your Roof Pitch
Enter your measurements to instantly calculate roof pitch, angle, slope, rafter length and pitch factor.
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