Roof Pitch Calculator
Convert roof pitch to angle and slope, then get the slope factor, total roof area, roofing squares, and rafter length from your building footprint.
A 6/12 pitch rises 6 inches for every 12 inches of horizontal run.
How to Calculate Roof Pitch and Area
Roof pitch is written as rise over run — the inches a roof climbs for every 12 inches it travels horizontally. A 6/12 pitch rises 6 inches per foot of run. To turn pitch into degrees, take the arctangent of the rise divided by 12: a 6/12 roof is about 26.6°, while a 12/12 roof is exactly 45°. The slope as a percentage is simply the rise divided by 12, times 100.
To find the actual roof area, multiply the building's footprint (including overhang) by the slope factor, √(rise² + 144) / 12, which stretches the flat footprint up the incline of the roof. Divide that area by 100 to get roofing squares, the unit shingles are sold in. For a simple gable, the rafter length is the half-span plus overhang, multiplied by the same slope factor — all of which this calculator computes live as you adjust the pitch.
Frequently Asked Questions
What does a 6/12 roof pitch mean?
A 6/12 pitch means the roof rises 6 inches vertically for every 12 inches of horizontal run. That works out to about a 26.6° angle — a common, moderately steep residential slope.
How do I convert roof pitch to degrees?
Take the arctangent of the rise divided by 12: angle = atan(rise / 12). A 6/12 pitch is atan(6/12) ≈ 26.6°, and a 12/12 pitch is exactly 45°.
How do I calculate roof area from pitch?
Multiply the building's footprint, including overhang, by the slope factor √(rise² + 144) / 12. Divide the result by 100 to get roofing squares, the unit shingles are sold in.
Turn Your Measurements Into a Real Floor Plan
Once you know your dimensions, generate a labeled, to-scale floor plan in seconds — then export it to DXF or build it in 3D. No CAD experience needed.
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