How to Calculate Roof Pitch?

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Understanding the pitch of your roof is essential for various roofing tasks, including installing new roofing materials, estimating material quantities, and ensuring proper drainage. The roof pitch refers to the steepness or slope of the roof surface.

In this blog post, we will guide you through the process of calculating roof pitch, equipping you with the knowledge needed to make informed decisions for your roofing projects. Whether you’re a homeowner in Brampton or a contractor looking for accurate measurements, this guide will help you calculate roof pitch effectively.

Gather the Required Tools:

Before you start calculating the roof pitch, make sure you have the necessary tools at hand. You will need a tape measure, a level (preferably one that’s at least 48 inches long), a pencil, and a notepad or a smartphone to record your measurements.

Measure the Rise:

The rise refers to the vertical distance from the top of the roof to the bottom, or in other words, the height of the roof. To measure the rise, position the level horizontally against the roof surface, ensuring it is perfectly level. Measure the distance from the bottom edge of the level to the roof surface. This measurement represents the rise.

Determine the Run:

The run refers to the horizontal distance from the edge of the roof to the highest point (ridge). To measure the run, locate a spot on the roof where you can measure a horizontal distance of 12 inches. This distance will serve as your reference point. Measure the horizontal distance from this reference point to the ridge of the roof. This measurement represents the run.

Calculate the Roof Pitch:

To calculate the roof pitch, you need to determine the ratio between the rise and the run. The most common way to express this ratio is in the form of X:12. For example, a pitch of 4:12 indicates that for every 12 inches of horizontal run, the roof rises 4 inches vertically.

To calculate the pitch ratio, divide the rise by the run. For instance, if the rise is 6 inches and the run is 24 inches, the pitch ratio would be 6:24 or simplified as 1:4. To convert this ratio to the X:12 format, divide both numbers by the run (24 inches in this case) and then multiply by 12. In our example, the roof pitch would be 3:12.

Understanding Roof Pitch Categories:

Roof pitches can be categorized into different ranges, each with its own characteristics and considerations. Here are a few common roof pitch categories:

  • Low Slope: Less than 3:12
  • Conventional Slope: 4:12 to 9:12
  • Steep Slope: 10:12 to 18:12
  • Very Steep Slope: Greater than 18:12

Keep in mind that the steepness of the roof can impact the choice of roofing materials, structural requirements, and installation techniques. Consult with a professional Brampton roofing company to determine the most suitable options for your specific roof pitch.


Calculating roof pitch is a fundamental step in various roofing projects. By following the steps outlined in this guide, you can accurately determine the slope of your roof, enabling you to make informed decisions when it comes to repairs, replacements, or new installations. If you’re unsure about performing the calculations yourself, it’s always advisable to seek the assistance of a reliable Brampton roofing company. Their expertise and knowledge will ensure that your roofing projects are executed with precision, efficiency, and in compliance with industry standards.



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