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Roof Pitch Calculator

Determine your roof’s pitch or slope from rise and run measurements — useful for material estimates and safety planning.

Rise & Run

Rise (vertical)

Run (horizontal)

How Pitch Is Expressed

Common format: X/12 Example: 6/12 means 6 inches of rise for every 12 inches of run

Your Roof Pitch

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How to Use the Roof Pitch Calculator

Roof pitch tells you how steep a roof is. It is essential for choosing the right roofing materials, estimating quantities, and understanding safety requirements when working on a roof.

Measure the rise The rise is the vertical height the roof climbs over a given horizontal distance. Use a level and measuring tape for accuracy.

Measure the run The run is the horizontal distance. In traditional roofing, the run is often set to 12 inches so the pitch can be expressed as a simple ratio (for example 4/12 or 6/12).

Enter the values Type the rise and run into the calculator. You can use inches or centimeters.

Get the results The calculator shows the pitch ratio (X/12), the angle in degrees, and the slope as a percentage.

⚠️ Safety First

Measuring a roof can be dangerous. Only work on a roof if you have the proper safety equipment and experience. When in doubt, hire a qualified professional. This calculator is for planning and estimation purposes only.

What Is Roof Pitch?

Roof pitch (also called roof slope) describes how steep a roof is. It is usually written as a ratio of rise to run, most commonly with a run of 12 (for example 4/12 or 8/12). The higher the first number, the steeper the roof.

Pitch Formula Pitch Ratio = Rise ÷ Run (expressed as X/12)
Angle (degrees) = arctan(Rise ÷ Run)
Slope % = (Rise ÷ Run) × 100

Common Roof Pitches & Their Uses

2/12 – 4/12 Low slope. Common on modern homes and some commercial buildings. Requires special low-slope roofing materials.

4/12 – 6/12 Standard residential pitch. Good balance of appearance, water shedding, and walkability.

7/12 – 9/12 Steeper roofs. Excellent water runoff. More difficult and expensive to work on.

10/12 and steeper Very steep. Dramatic look but requires special safety gear and experienced crews.

How to Measure Rise and Run Safely

The classic method uses a level and a tape measure:

Place a level against the roof surface (or a rafter from inside the attic).
Measure 12 inches horizontally along the level — this is your run.
Measure the vertical distance from the end of the level down to the roof surface — this is your rise.

You can also measure a larger run (for example 24 or 36 inches) and the calculator will still give you the correct pitch ratio.

Why Roof Pitch Matters

Material Choice Some roofing materials (like certain shingles or metal panels) have minimum pitch requirements.

Water Shedding Steeper pitches shed water and snow more effectively.

Labor & Safety Steeper roofs cost more to install and require extra safety measures.

Aesthetics Pitch strongly affects the overall look and style of a house.

Roof Pitch Calculator FAQ

What is a 6/12 roof pitch?

A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. It is a common residential pitch (about 26.6 degrees) that balances appearance, drainage, and workability.

How do I convert roof pitch to degrees?

Use the formula: degrees = arctan(rise ÷ run). The calculator does this automatically and shows the angle in degrees.

What is considered a low-slope roof?

Roofs with a pitch of 3/12 or less are generally considered low-slope. They often require specialized roofing systems instead of standard asphalt shingles.

Can I calculate pitch from the attic?

Yes. Measuring the rise and run on a rafter from inside the attic is often safer and more accurate than measuring on the roof surface.

Does roof pitch affect material quantity?

Yes. Steeper roofs have more surface area than the simple footprint of the house, so material estimates must account for the pitch (or use a pitch factor).