Roof pitch chart — 32 pitches on one sheet

The slope factor converts area and the hip factor converts length, and they are never interchangeable. Multiply a footprint by the slope factor to get the roof surface above it. Multiply the run of a common rafter by the hip factor to get the length of the hip or valley that meets it at the corner. Both come out of the same pitch, but one is built on a right triangle in a vertical plane and the other on a diagonal across a square, which is why the hip column starts at 1.4144 while the slope column starts at 1.0002.

Because low-slope roofs get measured too, and the numbers down there are the ones people get wrong. A 1/4:12 fall is what a built-up or single-ply membrane roof is designed to, and it is also the drainage slope written into a lot of deck and porch details. The rows exist so that a 1/2:12 reading has somewhere to land rather than being rounded up into a pitch that would carry shingles.

It is the most common floor rather than the most common roof. Builders gravitate to the 4:12 to 6:12 band because it is the shallowest range that is unambiguously in single-underlayment territory, it is still walkable, and it uses less material than anything steeper. Steeper pitches show up where the roof is architectural — a 9:12 or 10:12 on a colonial, 12:12 and beyond on a Tudor or an A-frame — and shallower ones where the roof is hidden behind a parapet.

Because the relationship is a tangent, not a straight line. A 6:12 is 26.57 degrees, nearly four degrees more than half of 45, and the gap widens as the table goes down: a 3:12 is 14.04 degrees rather than 11.25. This is the single most useful reason to keep a chart rather than trust a mental ratio, and it is why the degree column here is carried to two decimals instead of being rounded to whole degrees the way most pitch tables do it.

Yes — the slope factor works on any plane at that pitch, however the planes are cut up. A hip roof, a gable roof and a shed roof over the same footprint at the same pitch all have the same surface area, because the hips only change where the material is cut, not how much sky the roof covers. What a hip roof changes is the waste: every hip and valley puts a cut edge through every course, which is an allowance you add after the area, not a different multiplier.

No — the table is code, and a manufacturer's warranty is a separate document that is often stricter. The IRC sets the floor at which a covering may legally be installed; the wrapper on the bundle can require a self-adhered underlayment, a particular fastening pattern or hand-sealing before it will pay out. Read both. Where they disagree, the stricter one is the one that governs what you actually do on the roof.

The site navigation, the ad slots, and the how-to, FAQ, related-tools and privacy sections — everything except the filtered table and the working-band notes underneath it. The column headings repeat at the top of a second page, and each row is kept whole rather than split across a page break. Filters are applied before printing, so a sheet trimmed to slate and ticked down to three rows prints as three rows.