The vertical rise of a roof for every 12 inches it runs horizontally, written as a ratio such as 6/12. A 6/12 roof climbs 6 inches per foot of run, which is an angle of about 26.6 degrees.

How do I measure pitch without getting on the roof?

Hold a 12-inch level horizontally against a rafter in the attic, or against the underside of a gable-end overhang, and measure straight down from the free end of the level to the surface. That vertical measurement in inches is the rise of an X-in-12 pitch.

What pitch are most San Antonio roofs?

Most single-family homes in the San Antonio metro carry a 4/12 to 8/12 pitch. Steeper roofs shed hail and rain faster but cost more to work on: everything above roughly 7/12 needs staging or harnesses.

Why does pitch change what a roof costs?

Twice over. The multiplier means a steeper roof simply has more surface over the same footprint, and past roughly 7/12 crews slow down and rig fall protection, which shows up in the labour rate.

Roof pitchcalculator

Measure 12 inches across and however many inches down, and this page turns it into the ratio, the angle and the number that converts a house footprint into actual roof surface. Geometry only; no prices on this page.

A roof stripped to its plywood decking mid-replacement, rafter lines visible under a clear sky. — Decking exposed mid-replacement

Pitch calculator

The working

Pitch ratio: not set
Angle: not set
Surface multiplier: not set
Walkability: not set
Roof surface: add a footprint
Roofing squares: add a footprint

Multiplier = √(rise² + 12²) / 12. Surface = footprint × multiplier. One roofing square is 100 sq ft of surface. Prices live in the cost calculator.

What the number means on a San Antonio roof

Pitch decides how much roof you actually own, how fast it sheds a Hill Country downpour, and whether a crew can walk it or has to rig for it.

Reading the ratio

A 4/12 roof is the gentle slope of most production-built homes; 6/12 to 8/12 is the range most of the metro’s newer subdivisions carry; 12/12 is a 45-degree A-frame plane. Below 3/12, shingles stop being an option at all and the assembly changes to a membrane or panel system, which is why a “flat” porch roof is priced differently from the house it is attached to.

Why steep costs more, twice

The multiplier is the honest part: a 12/12 roof carries 41% more surface than its footprint suggests, and every square of it needs material. The second cost is slower: past roughly 7/12 a crew cannot simply walk the plane, so staging, harnesses and slower tear-off show up in the labour rate. Neither is padding; both are geometry.

Pitch and hail

Steeper planes take hail at a shallower glancing angle, which is why the same storm can bruise a 4/12 roof and leave its 10/12 neighbour largely alone. If you are reading this after a storm, the cost guide covers what an insurance scope actually pays for.

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