Roof Pitch Calculator

What Is Roof Pitch?

Roof pitch is the steepness of a roof expressed as the ratio of vertical rise to horizontal run. Written as rise/run, a 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal distance. It's the standard way roofers and building codes describe slope.

How to Measure Roof Pitch

There are a few ways to measure pitch on an existing roof. The simplest is to use a 2-foot level and a tape measure. Hold the level horizontally against the roof, then measure the distance from the end of the level down to the roof surface. That's the rise in a 24-inch run, which you divide by 2 to get the rise in a 12-inch run (the standard way pitch is expressed).

Why Pitch Matters for Estimating

The steeper the pitch, the more actual surface area the roof has compared to its footprint. A 10/12 pitch roof has 30% more surface than its footprint would suggest — which means 30% more shingles, underlayment, and labor. Miss the pitch adjustment and you'll under-order materials and under-bid the job.

Pitch Categories

• Flat (0/12 – 2/12): Requires membrane roofing (TPO, EPDM, modified bitumen). Shingles don't work.
• Low slope (2/12 – 4/12): Shingles work but need ice and water shield across the entire roof.
• Standard (4/12 – 8/12): The sweet spot for residential. Most common pitch range.
• Steep (8/12 – 12/12): Harder to walk, needs fall protection, more labor time.
• Very steep (12/12+): Roof jacks and scaffolding required. Labor costs climb fast.

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