Roof Pitch Calculator

• •Use the Roof Pitch Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
• •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
• •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
• •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.

Roof pitch describes the steepness of a roof, expressed as the ratio of vertical rise to horizontal run (e.g., 6:12 means the roof rises 6 inches for every 12 inches of horizontal distance). This calculator converts that ratio into the slope angle in degrees, computes the slope factor for adjusting flat-area measurements to actual roof area, and estimates rafter length based on the building span. Whether you are ordering shingles, planning a roof replacement, or designing a new structure, knowing the pitch is essential. Steeper roofs shed water and snow more effectively but require more material and are more difficult to work on safely.

• !Confusing pitch ratio with angle in degrees -- a 6:12 pitch is 26.6 degrees, not 6 degrees.
• !Forgetting to add eave overhang to the rafter length calculation.
• !Using pitch where slope is required, or vice versa.
• !Not applying the slope factor when converting building footprint to actual roof area.