How to Calculate Roof Pitch (Rise Over Run, Degrees, and Multiplier)

By Jorge Sanchez · April 20, 2026 · 5 min read

Knowing your roof pitch is essential for calculating materials (shingles, underlayment), planning solar panel installation, checking building code compliance, and hiring contractors. Here's how to measure and express it correctly.

What Is Roof Pitch?

Roof pitch describes how steeply the roof slopes. It's expressed as a ratio of rise (vertical height) to run (horizontal distance) — always with 12 as the run.

How to Measure Roof Pitch

You need a level and a tape measure. From inside the attic is easiest:

1. Hold a 12-inch level horizontally against a rafter
2. Make sure the bubble shows perfectly level
3. From the 12-inch mark on the level, measure vertically up to the rafter
4. That measurement in inches is your rise — your pitch is rise/12

From outside the roof: stand at a gable end and estimate from the ground, or use a smartphone inclinometer app.

Roof Pitch Reference Table

How to Calculate Roof Area from Pitch

The pitch multiplier converts flat (footprint) area to actual roof surface area:

Example: A house with a 1,500 sq ft footprint and a 6:12 pitch:

Add 10–15% for waste when ordering shingles. So order for about 1,845–1,929 sq ft, or approximately 19–20 squares (one roofing square = 100 sq ft).

Common Roof Pitches by Region

• Snow country (Midwest, Northeast): 6:12 to 12:12 — steeper so snow slides off
• Mild climates: 4:12 to 6:12 — the most common in the U.S.
• Sun belt / flat areas: 2:12 to 4:12 — low pitch, often with metal roofing
• Commercial buildings: Under 2:12 — requires special waterproofing membranes