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Roofing Pitch Calculator

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Roofing Pitch Calculator

Roofing pitch calculators calculate the slope of an elevation based on input (such as rise and run) and output to ratio, degree or percentage format. This enables the designer to have accurate measurements quickly for use in the design process, selection of material, and the planning for construction of the entire elevation.

Roofing Pitch Calculator
Ratio: -
Percentage: -
Angle: -

What is a Roofing Pitch Calculator?

The roofing pitch calculator is a device that allows users to accurately determine the steepness of a roof. By entering a few basic measurements, the user does not have to perform the calculations and can receive the roof pitch in various formats.

The Roofing Pitch Calculator has become an important tool for contractors when providing bids to prospective clients. Homeowners may use the calculator to determine the amount of materials needed prior to purchasing them. When architects are designing a project they can use this tool to ensure compliance with local building code requirements and compatibility with the proposed roof system.

Why is Roofing Pitch Important?

A Roofing Pitch Calculator affects nearly every aspect of a roofing project, from the type of materials available to the cost of those materials to the ability of the roof to drain water effectively.

Steeply pitched roofs shed rain and snow fairly quickly, so they are often used in locations that experience high precipitation amounts. Lower-sloped or ‘flat’ roofs have to use special types of waterproofing material because the water sits on them longer.

Pitch is used by roofers to establish how many shingles will be required for the job, and building inspectors check the pitch of roofs to determine whether they meet local building codes. Insurers may provide lower premium rates for roofs with lower pitches than those with higher pitches, due to the increased danger associated with working on a more steeply shaped or configured roof structure.

Roofing Pitch Formula and Calculation Method

Roofing Pitch Calculator is most often expressed as a ratio of rise to run, which means the amount the roof rises or falls up or down vertically, over a distance measured horizontally. In general, the rise is how many inches of vertical height your roof has for every twelve inches of horizontal length (the run) measured at the same position.
Roof Pitch Formula:

Pitch= (Rise ÷ Run) × 12

Where the “rise” variable is the height of the roof in inches and the “run” variable is the distance measured in inches (12). This gives the pitch of the roof as a mathematically expressed quantity of “X in 12” (e.g., 3 in 12), or as a fraction, “X/12” (e.g., 3/12).

You can also express pitch in degrees or percentages:

Degrees: arctangent(Rise ÷ Run) × (180 ÷ π)

Percentage: (Rise ÷ Run) × 100.

Most builders prefer to communicate a pitch on construction sites using ratio format, because it is simpler to convey.

Calculating Roof Pitches Step-By-Step
If you measured a roof and determined that it had a rise of 6 inches over a run of 12 inches, the following process would be used to determine its pitch.

Step 1: Gather Your Measurements

For this example, we know that the “rise” is 6″ and the “run” is 12″.

Step 2: Plug The Measurements Into The Equation.

  a. Pitch= (6 ÷ 12) × 12
  b.Pitch= 0.5 × 12
  c. Pitch= 6

Step 3: Write The Pitch as a Ratio

The pitch of this roof is 6/12 or “6 in 12”.

Step 4 (Optional): Write The Pitch as Degrees

  a. Angle= arctangent(6 ÷ 12)

  b. Angle= arctangent(0.5)

  c. Angle ≈ 26.57 Degrees

Step 5 (Optional): Write The Pitch as a Percentage

  a. Percentage= (6 ÷ 12) × 100

  b. Percentage= 50%

This roof has a moderate slope. While the slope will work with normal asphalt roof shingles, the pitch of this roof will create no significant safety issues when installing the shingles.

Using The Roofing Pitch Calculator

A roofing pitch calculator allows you to instantly convert rise and run measurements collected from your roof into pitch ratios, degrees, percentages, and material estimating pitch factors without having to complete the math each time.

Here’s how it works:

Simply enter the rise and run measurements taken from your roof, and the Roofing Pitch Calculator will quickly calculate the corresponding pitch for you in a variety of formats including ratio, percentage, degree, and in some cases, using the material estimating pitch factor.

Why use Roofing Pitch calculator instead of doing it manually?

The importance of speed on the Job Site cannot be overstated. Roofing Pitch Calculator can prevent miscalculating geometry by eliminating arithmetic mistakes, primarily due to odd measurements or conversions from Metric to Imperial measurements. Calculators provide a way of “seeing” all the typical ways that one would represent a particular Roof.

Some Roofing Pitch Calculator also contain features that assist with other aspects of Roof Planning such as Estimating Rafter Lengths or Roof Area. Even though these features will help when planning the Purchase of Materials, they will do nothing but provide the same Function as a Roof Pitch Calculator by converting basic measurements into usable Pitch Data.

Our Roofing Pitch Calculator can read both Imperial and Metric Input and provides you with the Results Back to You in All of the Standard Formats Used by Contractors and Builders.

Roofing Pitch Calculator Accuracy, Limitations, and Assumptions

A roof pitch calculator will provide a correct result based on the measurements provided by you into it. If you provide an estimate for the rise or run, then the result will be as accurate as your estimate.

When results may vary:

Older and Settled Buildings often have different degrees of slope in different sections. Therefore, if you measure 6/12 on one side then the other side may measure 5.5/12. If you need accurate measurements, please measure in several areas of the building.

Complicated roof types that have multiple valleys, slopes, and/or dormers will need separate calculations for each section. Thus, one calculator result will not represent an entire roof.

Important notes:

While aerial or satellite measurements are useful as a rough guide, you should always confirm elevation directly before ordering materials or applying for permits, as they cannot be used as accurate substitutes.

When measured with thermal variations, it affects the accuracy of measurement. Example: Metal tape measures expand due to heat and contract due to cold; therefore, the measurement may be off by a fraction of an inch on long runs.

Building codes establish minimum pitch slopes for roofing materials, and calculators provide the pitch but do not provide information on whether they are within local requirements. Verify local requirements independently from any calculator used to determine the pitch.

Frequently Asked Questions

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

If you can access the interior attic space, simply measure from there. Locate a rafter and then extend horizontally away from the peak of your roof by 12 inches and drop vertically down to the rafter. This vertical measurement is your rise to pitch ratio. Or you can use a pitch gauge tool from ground level if you have an unobstructed view of the edge of the roof to measure the slope.

Generally speaking, asphalt shingles perform best on roofs that have a pitch greater than 4 inch x 12-inch, but there are a few manufacturers that will allow the installation of those same shingles down to pitch of 2 inches x 12 inches with special underlayment or a specific manufacturer’s instructions. Shingles have a longer life span when installed on steeper pitch roofs than the same shingles installed on a lesser pitch roof because rainwater drains faster on steeper pitch roofs..

Yes, almost all modern calculators are able to accept both metric system and imperial system values as inputs into their respective programs. Always make sure you remain consistent with the units of measurement that you are using; do not mix centimeter measurements into an inches measurement in the same calculation. The Roofing Pitch Calculators work the same way regardless of what measurement system you’re using.

While often used interchangeably, Roofing Pitch Calculator is technically the rise-to-run ratio of an object (like a roof), and slope is measured in degrees. In practice, builders and contractors use both words to mean the same thing.

For estimates of materials and general planning, measurements within 1/4″ (1 inch) of a quarter must be used for an approximate projection of what it will be. If you are providing specifications for engineered structures, or complex custom assemblies, you may also want to include a tolerance of 1/8″ (or less). The tighter the tolerance, the more careful you must be when measuring.

Yes. Metal roofing may be installed on sloping roofs with a pitch of 1/12 (one inch per foot) or greater, provided proper sealing methods are used. Tile (clay/concrete) roofs typically need at least a pitch of 4/12 (four inches of rise for every twelve inches of run) to properly drain water and avoid premature material failure. Built-up (asphalt, tar, etc.) and modified bitumen systems can be used on roofs that are almost flat. Be sure to check the manufacturer’s specifications before installing. Different products have different requirements.

Water will not drain off a low sloped roof and therefore will pool on the surface, eventually causing leaks and premature failure of the roofing material. Most manufacturers of roofing material will void any warranty if their product is installed on a roof that does not meet the minimum pitch requirement. Using an inappropriate product on a low sloped roof is one of the leading causes of roofing issues.

Steeper roofs require more safety gear, take longer to install, and may require more structural support. Material costs could also be higher for steeper roofs than for flatter roofs covering the same footprint due to the fact that the surface area is greater.

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