Degrees to Slope Calculator Roof

This degrees to slope calculator converts roof pitch angles in degrees to slope percentages. Understanding roof slope is essential for construction, roofing, and architectural design. The calculator provides both the slope percentage and rise/run ratio for your roof.

How to Use This Calculator

Using our degrees to slope calculator is simple:

Enter the roof pitch angle in degrees in the input field
Click the "Calculate" button
View the results showing the slope percentage and rise/run ratio
Use the reset button to clear the calculator for new calculations

The calculator will display the slope percentage (how steep the roof is) and the rise/run ratio (the actual dimensions of the roof's slope).

Formula Explained

The relationship between roof pitch angle in degrees and slope percentage is based on trigonometry. The formula used is:

Slope Percentage = tan(θ) × 100

Where θ is the roof pitch angle in degrees. The rise/run ratio can be calculated by taking the tangent of the angle and simplifying the fraction.

For example, a 30° roof pitch has a slope of approximately 57.7% and a rise/run ratio of 1:1.732.

Worked Examples

Example 1: 20° Roof Pitch

For a roof with a 20° pitch:

Slope Percentage: 36.4%
Rise/Run Ratio: 1:1.732

Example 2: 45° Roof Pitch

For a roof with a 45° pitch:

Slope Percentage: 100%
Rise/Run Ratio: 1:1

Example 3: 10° Roof Pitch

For a roof with a 10° pitch:

Slope Percentage: 17.6%
Rise/Run Ratio: 1:5.671

Common Roof Angles

Here are some common roof pitch angles and their corresponding slope percentages:

Angle (Degrees)	Slope Percentage	Rise/Run Ratio
5°	8.75%	1:11.43
10°	17.63%	1:5.671
15°	26.79%	1:3.732
20°	36.40%	1:2.747
25°	46.63%	1:2.144
30°	57.74%	1:1.732
45°	100%	1:1

Frequently Asked Questions

What is the difference between roof pitch and slope percentage?: Roof pitch is measured in degrees, while slope percentage represents how steep the roof is as a percentage. For example, a 30° roof pitch has a 57.7% slope.
How do I measure the angle of my existing roof?: You can measure the angle using a protractor or by measuring the rise and run of the roof and calculating the angle using the arctangent function.
What is the steepest angle a roof can have?: The steepest angle for a residential roof is typically 45°, though some commercial roofs can be steeper. Very steep roofs require special materials and construction techniques.
Can I use this calculator for flat roofs?: Flat roofs have a 0° pitch and 0% slope. While you can enter 0° in the calculator, flat roofs have different construction requirements than pitched roofs.