Home›Calculators›Construction›Roof Pitch Calculator

Roof Pitch Calculator

Construction

Find your roof's pitch angle in degrees and percent slope from simple rise and run measurements. Instant results for framing, roofing, and DIY projects.

124
624

Pitch Angle

26.57
Pitch Percent Slope
50

This calculator computes your Pitch Angle, Pitch Percent Slope from the values you enter.

Inputs
RiseRun
Outputs
Pitch AnglePitch Percent Slope

What is a Roof Pitch?

A Roof Pitch Calculator converts simple rise and run measurements into a roof's pitch angle (in degrees) and percent slope, two standard ways of expressing roof steepness alongside the traditional "X/12" notation used in construction. Roof pitch affects everything from material selection and drainage performance to attic space and rafter length, making it one of the first measurements needed when planning roofing work.

Whether you're measuring an existing roof to confirm its pitch or verifying a design meets a material's minimum slope requirement, this calculator gives you the conversion instantly. Pair it with the Rafter Length Calculator once you know your pitch, or the Roof Shingle Calculator for material quantity estimates.

How to use this Roof Pitch calculator

  1. Measure your roof's Rise in inches over a convenient horizontal distance using a level and tape measure.
  2. Enter the corresponding Run in inches (commonly 12 inches for a standard measurement).
  3. Review the Pitch Angle result in degrees.
  4. Review the Pitch Percent Slope result as a percentage.
  5. Compare either figure against your roofing material's minimum slope specification, or use the result with the Rafter Length Calculator for framing calculations.

Formula & Methodology

The calculator converts rise and run into angle and percent slope:

Pitch Angle = arctan(Rise ÷ Run)

Pitch Percent Slope = (Rise ÷ Run) × 100

Worked example: For a measured rise of 6 in over a 12 in run:

Pitch Angle = arctan(6 ÷ 12) = arctan(0.5) ≈ 26.57°

Pitch Percent Slope = (6 ÷ 12) × 100 = 50%

This corresponds to a traditional "6/12" roof pitch — a common, moderate pitch suitable for most standard roofing materials.

Frequently Asked Questions

Roof pitch describes the steepness of a roof, traditionally expressed as the rise (vertical height) per 12 inches of run (horizontal distance), such as a '6/12' or '6-in-12' pitch. This calculator converts your measured rise and run into both the pitch angle in degrees and the percent slope, two other common ways of expressing roof steepness.
Place a level horizontally against the roof surface extending exactly 12 inches (or measure any convenient run distance), then measure the vertical distance from the end of the level down to the roof surface — that vertical measurement is your rise for the given run.
Most residential roofs in the US fall between 4/12 and 9/12, with 6/12 being a common middle-ground pitch that balances water drainage, snow shedding, attic space, and material cost. Steeper pitches (10/12 and above) are used in heavy snow regions or for specific architectural styles.
Pitch angle expresses roof steepness in degrees from horizontal, while percent slope expresses it as a percentage (rise divided by run, times 100) — both describe the same steepness using different conventions, and this calculator provides both alongside the traditional X/12 pitch notation.
Low-pitch roofs (below 2/12) generally require membrane or low-slope roofing systems rather than standard shingles, while steeper pitches can use most standard roofing materials but require more material overall due to increased surface area — always check your roofing manufacturer's minimum pitch rating before choosing shingles.
A steeper pitch increases the rafter's rise for a given horizontal run, which increases the total rafter length via the Pythagorean relationship — use the [Rafter Length Calculator](/rafter-length-calculator/) alongside this tool once you know your roof's pitch.
Yes, entering your measured rise and run gives you the pitch angle and percent slope, which you can compare directly against a roofing material's minimum slope requirement (often stated as a percentage or minimum X/12 ratio) to confirm compliance.
Yes, steeper pitches create more vertical headroom near the roof's centerline, which is why steep-pitched roofs (including gambrel-style roofs) are often chosen when maximizing attic or loft storage and living space is a design priority.
Small measurement errors in rise or run can noticeably shift the calculated pitch angle, so measure as precisely as possible with a level and tape measure, and consider averaging multiple measurements along the roof if it's not perfectly uniform.
Also known as
roof pitch to angle calculatorrise over run roof calculatorroof slope calculatorroof pitch percent calculatorroof angle calculator