Roof Run Calculator

How to Use the Roof Run Calculator

Our roof run calculator helps you calculate the horizontal distance from the roof centerline to the outside wall or eave. Enter the roof pitch and the vertical roof rise, then select the appropriate unit for your measurement.

The calculator uses your roof pitch and rise to determine the roof run. It also provides related measurements such as roof angle, roof slope, roof rise, and rafter length.

1. Enter the roof pitch, such as 6:12.
2. Enter the vertical roof rise.
3. Select the unit for the roof rise.
4. Click Calculate Roof Run.
5. Review the calculated roof run and related measurements.

What Is Roof Run?

Roof run is the horizontal distance used to describe the position of a sloped roof. For a typical gable roof, the run is measured horizontally from the roof centerline or ridge toward the outside wall or eave.

Roof run is an important measurement when working with roof pitch, roof rise, rafter length, and roof framing calculations. Knowing the run helps you understand how far a roof section extends horizontally for a given vertical rise.

Roof run is different from the rafter length. The run is a horizontal measurement, while the rafter length follows the slope of the roof.

Roof Run Formula

When the roof pitch is expressed as rise per 12 inches of horizontal run, the roof run can be calculated using the following formula:

For example, if the roof has a 6:12 pitch and the roof rise is 6 feet:

Therefore, a roof with a 6:12 pitch and a 6-foot vertical rise has a horizontal roof run of 12 feet.

What Does This Roof Run Calculator Calculate?

This calculator is designed to calculate the horizontal roof run while also showing several related roof measurements.

Roof Run Example

Suppose you have a roof with a 6:12 pitch and a vertical rise of 6 feet.

This example shows how roof pitch and rise are related to the horizontal run. As the roof pitch becomes steeper, the same vertical rise requires a shorter horizontal run.

Roof Run vs. Roof Rise

Roof run and roof rise describe two different directions of a roof measurement.

Together, roof rise and roof run describe the basic geometry of a sloped roof and are used to determine roof pitch, slope, angle, and rafter length.

Roof Run vs. Rafter Length

Roof run and rafter length are not the same measurement. Roof run is measured horizontally, while rafter length is measured along the slope of the roof.

For example, with a 6-foot rise and a 12-foot run, the rafter is longer than the horizontal run because it follows the diagonal slope of the roof.

The relationship between the rise, run, and rafter length can be represented by the Pythagorean theorem:

Roof Pitch and Roof Run

Roof pitch describes how much a roof rises vertically for every 12 inches of horizontal run. For example, a 6:12 roof pitch means the roof rises 6 inches for every 12 inches of horizontal run.

For the same roof rise, a steeper pitch produces a shorter horizontal run, while a lower pitch produces a longer horizontal run.

Roof Run Measurements and Units

Roof measurements can be expressed using different units. This calculator allows the roof rise to be entered in commonly used units so you can work with the measurements available to you.

• Feet (ft) — commonly used for larger roof measurements.
• Inches (in) — useful for detailed framing measurements.
• Meters (m) — commonly used in metric measurements.
• Centimeters (cm) — useful for smaller metric measurements.

Always make sure the selected unit matches the measurement you enter. Consistent units help avoid calculation errors.

Important Information

Related Calculators

Explore our other roofing calculators to calculate roof pitch, slope, angle, and rafter measurements.