4:12
Roof Pitch
18.43°
Angle in Degrees
33.3%
Grade Percentage
1054
Actual Roof Area (sq ft)
Roof pitch is a measure of the steepness or slope of a roof. It is commonly expressed as a ratio of rise over run. For example, a 4:12 pitch means that for every 12 inches of horizontal distance (the run), the roof rises 4 inches vertically. This notation is widely used in the construction and roofing industries across North America.
Knowing your roof's pitch is crucial when planning a roofing project, estimating materials, or determining if certain roofing systems (like asphalt shingles versus flat roof membranes) are suitable for your home. Steeper roofs tend to shed water and snow more effectively, while lower slope roofs require specialized underlayment to prevent water intrusion.
While the standard ratio (e.g., 6:12) is most common among contractors, you may sometimes need the roof angle in degrees or as a grade percentage.
One of the biggest mistakes DIY roofers make is using their home's flat footprint (the square footage of the rooms below) as the total roof area. Because the roof is angled, its actual surface area is always larger than the flat footprint underneath it.
Our calculator determines an area multiplier based on your specific pitch. For a flat roof, the multiplier is 1.0. For a steep 12:12 roof, the multiplier is approximately 1.41. By entering your home's footprint area, the calculator automatically applies this multiplier to give you a more accurate estimate of the total square footage of roofing material you'll need.
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