Calculate roof pitch, slope angle, and rafter length from your roof's rise and run. Essential for roofing estimates, material calculations, and building code compliance.

What Is Roof Pitch?

Roof pitch expresses steepness as rise over a 12-inch run. A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal distance. Pitch determines which roofing materials you can use, how quickly water and snow shed, and total material costs.

Common Roof Pitches and Uses

• 1/12 – 3/12: Low-slope; requires rolled roofing, membrane, or metal panels
• 4/12 – 6/12: Most common for US homes; works with asphalt shingles, walkable for repairs
• 7/12 – 9/12: Steep; excellent snow shedding, common in northern states
• 10/12+: Very steep; Victorian and A-frame styles, premium installation cost

How Pitch Affects Material Costs

Steeper roofs need more material. Multiply your building's footprint area by the pitch factor: a 4/12 pitch multiplies area by 1.054, 6/12 by 1.118, 8/12 by 1.202, and 12/12 by 1.414. A 2,000 sq ft footprint with a 6/12 pitch actually needs about 2,236 sq ft of roofing material.

FAQ

What is the most common roof pitch?
4/12 to 6/12 covers most American residential construction — steep enough for shingle warranties, gentle enough for safe installation.

Can I put shingles on a 2/12 pitch roof?
Most manufacturers require 4/12 minimum for standard installation. Between 2/12 and 4/12, you need double underlayment or special low-slope shingles.

How do I measure my roof pitch?
From the attic, hold a 12-inch level horizontally against a rafter and measure the vertical distance from the level's end to the rafter — that's your rise.