Construction

Roof Pitch Calculator

Pitch, angle & multiplier in one stepActual roof area from floor footprintCommon pitch reference table included

Enter Roof MeasurementsFree · Instant

Rise (inches)

Vertical height (inches)

Run (inches)

Horizontal run (typically 12)

Floor Footprint (sq ft), optional

Used to calculate actual roof surface area

Roof Pitch Results

6/12

Pitch

26.6°

Angle

1.118×

Multiplier

Category: Steep Slope

Pitch Visualization

Run: 12"

Rise: 6"

Actual Roof Surface Area

1,342 sq ft

1,200 sq ft floor × 1.118 pitch multiplier

How Your Pitch Compares

1/12 4.8°

2/12 9.5°

3/12 14.0°

4/12 18.4°

5/12 22.6°

6/12 ← Your Pitch26.6°

8/12 33.7°

12/12 45.0°

How Roof Pitch Is Calculated

Pitch = Rise / Run (expressed as Rise/12)
Angle = arctan(Rise ÷ Run) × (180 ÷ π)
Multiplier = √(Rise² + Run²) ÷ Run
Actual Area = Floor Footprint × Multiplier

The pitch multiplier is the key number for material estimates. A 6/12 roof has a multiplier of about 1.118, meaning every 1,000 sq ft of floor area requires 1,118 sq ft of roofing material.

Who Is This Calculator For?

🏗️

Roofers & Contractors

Calculate material quantities and labor requirements for any pitch.

🏠

Homeowners

Understand your roof pitch before buying shingles or planning repairs.

📐

Architects & Designers

Verify pitch specs match local code and material requirements.

💰

Material Estimators

Convert floor footprint to actual roof area for accurate ordering.

How to Use This Calculator

Enter the rise

The rise is how many inches the roof goes up for every unit of run. For a 6/12 pitch, rise = 6.

Enter the run

Standard run is 12 inches. Leave as 12 unless your pitch is expressed differently.

Enter floor footprint (optional)

Your home's floor area in sq ft. Used to calculate actual roof surface area.

Read your pitch

The result shows your pitch as Rise/Run, angle in degrees, and pitch multiplier.

Use the multiplier for materials

Multiply your floor footprint by the multiplier to get the true roof area.

Add 10–15% for waste

Always order extra shingles or underlayment to account for cuts and overlap.

Worked Example

A 1,500 sq ft ranch home has a 5/12 roof pitch. What is the actual roof surface area?

Pitch: 5/12
Angle: arctan(5/12) = 22.6°
Multiplier: √(5² + 12²) / 12 = √169 / 12 = 1.083
Actual Area: 1,500 × 1.083 = 1,624 sq ft
+15% waste = ~1,868 sq ft of materials needed

Common Roof Pitch Mistakes

Using floor area as roof area

The floor footprint is always smaller than the actual roof surface. Always apply the pitch multiplier.

Ignoring valleys and hips

Complex roofs with hips, valleys, and dormers have more surface area than a simple gable. Add extra waste.

Confusing pitch and slope

Pitch is rise-over-run (e.g., 6/12). Slope angle in degrees is different: a 6/12 pitch is 26.6°, not 50%.

Ordering by square footage alone

Roofing is often sold in 'squares' (100 sq ft). Convert your total area to squares when ordering shingles.

Skipping the waste factor

For simple roofs add 10%. For complex roofs with cuts at ridges, valleys, and hips, use 15–20%.

Frequently Asked Questions

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Sources & References

National Roofing Contractors Association: The NRCA Roofing Manual

NRCA · nrca.net

International Residential Code: Chapter 9, Roof Assemblies

IRC · iccsafe.org

Residential Steep-Slope Roofing Material Guide

Asphalt Roofing Manufacturers Association · arma.org

Written By

Dan Kowalski

Licensed roofing contractor, 15+ years residential & commercial

Dan runs a roofing company in the Midwest and has installed and repaired roofs on thousands of homes. He frequently contributes to trade publications on residential roofing best practices.

Pitch Reference

Pitch	Angle	Type
1/12	4.8°	Nearly flat
2/12	9.5°	Low slope: requires special materials
3/12	14.0°	Low slope
4/12	18.4°	Standard residential
5/12	22.6°	Standard residential
6/12	26.6°	Moderate
8/12	33.7°	Steep
12/12	45.0°	Very steep

💡 Pro Tip

When ordering roofing materials, add 10–15% waste factor to your calculated surface area. For complex roofs with hips, valleys, or dormers, increase waste to 15–20%.

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