Use our free Roof Pitch Calculator app to instantly convert rise and run into slope percentage, roof angle in degrees, and rise-over-run ratio — no math required. For a full list of conversions, see our Roof Pitch Chart.

✅ Instant results with just two numbers
✅ Works for gable, hip, shed, or flat roofs
✅ Saves time on material estimates and code compliance

How Rise and Run Define Roof Pitch

Every roof pitch is based on two simple numbers: the rise (how high the roof goes up) and the run (how far it goes across). Together, they create the ratio that describes how steep a roof is.

In roofing, the run is always standardized at 12 inches (one foot). The rise is what changes. So if a roof climbs 4 inches for every 12 inches of run, it’s called a 4/12 pitch. This shorthand makes it easy for roofers and builders to compare slopes.

Here’s what that looks like in practice:

• 3/12: rises 3 inches per 12 inches of run (gentle slope)
• 6/12: rises 6 inches per 12 inches of run (balanced, common slope)
• 12/12: rises 12 inches per 12 inches of run (very steep)

This measurement system is similar to the concept of slope in math or the tangent function in trigonometry. Engineers and architects also convert these ratios into degrees. For instance, a 6/12 pitch equals about 26.57°.

Knowing your roof pitch isn’t just trivia—it affects which roofing materials are suitable, how quickly water or snow drains off, and even the overall style of your home.

How to Use the Roof Pitch Calculator

1. Enter the rise — vertical distance to the peak.
2. Enter the run — horizontal distance (often 12″).
3. Click “Calculate” to see slope %, angle (°), rafter length, and roof type.

This tool works for homeowners, contractors, DIY builders, or anyone needing fast, accurate roof pitch information.

Why Roof Pitch Matters

• Style & curb appeal — defines the look (gable, hip, shed, etc.).
• Material fit — steeper roofs shed water/snow better and expand material options.
• Code & warranties — many products require minimum slopes.
• Accurate takeoffs — slope affects area, waste factors, and labor.

Whether you’re installing shingles, metal panels, or checking drainage, knowing your roof pitch is critical to avoid mistakes.

Roof Pitch Formula

Here are the key formulas our calculator uses to convert rise and run into slope, angle, and length:

• Pitch (ratio) = Rise ÷ Run
• Pitch (%) = (Rise ÷ Run) × 100
• Angle (°) = arctangent (Rise ÷ Run)
• Rafter length = √(Rise² + Run²)

Explore Roof Pitch Types

Want to see how different roof pitches compare? Our guides for 1/12 through 12/12 cover slope percentage, angle in degrees, rafter length, and popular roof styles. The table below groups these pitches into common slope categories with examples.

Slope	Pitch	Common Roof Types & Examples
Low Slope	1/12, 2/12, 3/12	Flat, skillion/shed, butterfly, green roofs, & commercial
Moderate	4/12, 5/12, 6/12	Gable, hip, Dutch gable, cross-gable, bungalow, shed
Steep	7/12, 8/12, 9/12	Tudor, Cape Cod, Gothic Revival, mansard upper slopes
Very Steep	10/12, 11/12, 12/12	A-frame, chalet, Victorian, Gothic-inspired homes