Having an accurate roof pitch is key for ordering the right amount of materials for a roofing job. The pitch of a roof can also impact safety planning, specialty tools needed, or even how many people you need on a crew. Roof pitch calculators and digital tools make it easy for roofers to get accurate pitches, easily.
Quickly: What is roof pitch?
Roof pitch refers to how many inches a roof goes up for every 12 feet in. For example, 4:12 would be a roof that rises 4 inches for every 12 inches deep. This would be a shallower roof than a 8:12 roof, which would rise 8 inches for every 12 inches deep.
This ratio can be written in a couple of formats and is best expressed in inches per foot. The most common of these formats are x:12 or x/12, which indicates the number of inches of rise for every 12 inches of run. For example, a roof that rises four inches for every 12-inch run has a 4/12 or 4:12 pitch.
Top 5 pitch tools for roofers
Heres our top 5 (and a bonus!) pitch calculators. If you're looking for more information on roof pitch, terms, and how to calculate them manually, scroll to the bottom.
If you've used Roofr for a satellite roof measurement before, you may have seen this tool. Roofr has a built-in feature that lets you use google maps and satellite images to calculate the pitch of a roof.
The easy-to-use tool takes you 5 seconds to get the pitch of a roof, and it automatically adjusts your measurements accordingly. That's the value of digital measurements!
If you haven't used Roofr before, it's free to get started.
Blocklayer.com is an old-fashioned website, but its calculator is useful for finding the connections between roofing pitch, angle, and grade. A slider lets you adjust the angle, and the other measurements instantly adjust as you drag the tab on the slider.
It's a very visual tool and lets you see how the relationship between the three measurements come together to form square corners. If you're a bit of a math or geometry nerd, or just love playing around with roofing tools, this is a great one.
3. Omni Calculator
Omni Calculator has a beautifully designed roof pitch calculator. You enter the rise and run of the roof, and can choose from several units of measurement, including feet, inches, and meters.
After you type in the rise and run, the calculator instantly tells you the rafter length, grade, and roof pitch in x:12.
The calculator will also tell you the roof pitch angle in degrees, radians, and more. Once you get the results from Omni Calculator, you can send them to yourself or save a unique link to your specific results.
Another great roof pitch calculator comes from MyCarpentry.com. You enter the rise and run, but you can only do so in inches. The slope calculator will also determine angle, rafter length, and pitch.
On its calculator page, MyCarpentry.com also includes roofing definitions and diagrams to help you better understand what to measure and what the calculator results mean.
For the roof pitch calculator on MyRooff.com, you need to know two of these three measurements: rise, run, and rafter length. Your measurements must be in inches. After you enter your two measurements, the calculator will determine the third measurement you did not enter.
The calculator has sliders you can use to adjust the measurements and instantly see updated numbers, as well as a handy, dynamic roof diagram that shows your measurements and calculations on it.
Manually measuring roof pitch
Even if you choose to use an online roof pitch calculator or one that helps you with other roof angles, you still want to know how to calculate a pitch manually.
To manually calculate a roof pitch, you want to measure:
- From the top of a roof ridge to 12 or 24 inches out. (24 inches off might be easier to measure or maneuver, but whatever works for you.)
- The height from that measurement down.
If you measure 24 inches out, you'll want to cut the height measurement in half, since pitch equals rise for every 12 inches.
You can measure with a tape measure, a square measure, a measuring stick, etc. It really doesn't matter as long as you can get a clear 90-degree angle when measuring down and out. You want a perfect 90-degree triangle when taking that measurement.
Here are some extra terms you'll need to know about roof pitch and measurements.
For a full list of roofing terms, check out our full glossary.
The pitch is the slope of a roof. It's measured in roofing by vertical rise in inches for every 12 inches of horizontal run. Or, how much a roof goes up for every foot out.
Pitch matters because it affects the area of a roof. A steep roof in a small space will have more area — and need more materials — than a shallow or flat roof.
Pitch determines what kind of roof you get, too. Different types of roofs or materials are more suitable for specific ranges of pitches, all depending on geographic area.
Factors like rain and snow runoff, as well as ice buildup, and how difficult it will be to walk on your roof, and the weight of materials can impact what pitches can have certain materials.
To calculate pitch, measure the height of the tallest part of the roof (the ridge), and measure from the outer edge of the bottom of the roof to directly under the ridge (the run). Then, simply divide the rise by the run.
A higher pitch roof will be steeper. A lower pitch roof will be more shallow.
Instead of using two-value ratios for pitch, we represent roof angles in degrees. The degree measures the angle where your house and the edge of the roof meet.
Knowing the angle comes in handy for activities like cutting roofing materials. Certain tools like saws are usually calibrated in degrees, so ratios won’t compute.
You can calculate the angle by taking the grade and multiplying it by an arctan. The equation looks like this: angle = arctan (grade). You might want to use an arctan calculator for this. The equation will give you the angle in radians. But, you can convert the radians to degrees. The equation to convert radians to degrees is: degrees = radians x 180° / 𝝅.
Let’s use the grade from the previous example, 33- percent. The equation will look like this: angle = arctan (0.3333). The result is 0.32 radians. Now, you can convert the radians into degrees. Use the conversion equation: degrees = 0.32 x 180° / 𝝅. In this case, 0.32 radians equals 18.43°.
It might be easiest to calculate the roof angle using a roof pitch calculator. Or, if you know your roof’s pitch, you can easily convert to the angle by using a conversion table.
Roof pitch calculators
You can use tools to help you calculate roof pitch, or you can manually measure it yourself. Roofing tech is always evolving to help roofers work more efficiently and spend less time taking physical measurements. Satellite measurements and pitch calculators are just two examples of roofing software that can help you work smarter.
If you want to learn more, we suggest you check out these blogs:
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