A slope describes how much a surface rises over a horizontal distance. It is commonly used for roads, ramps, roofs, drainage, land grading, and landscape slopes where the steepness of a surface needs to be measured.

The slope percentage calculator uses two inputs: rise and run. After you enter them, it calculates the slope percentage, angle, ratio, and slope length automatically. The visual diagram shows how these measurements relate to the slope.

What Are Rise and Run?

Rise is the vertical change between two points on a slope. It tells you how much the surface moves upward. For example, a rise of 5 m means the surface moves up 5 meters between two points.

Run is the horizontal distance. It represents the distance between the starting and ending points, not the length of the inclined surface. For example, a run of 20 m means the horizontal distance between the two points.

To get a correct result, use the same unit for both measurements. For example, you can enter both rise and run in meters, feet, inches, or another matching unit.

How to Use the Slope Percentage Calculator

The calculator requires only the rise and run as inputs.

1. Enter the rise

Enter the vertical change in the Rise field. 

2. Enter the run

Enter the horizontal distance in the Run field. 

3. Check the results

Click Calculate. The calculator provides the slope percentage, angle, ratio, and slope length.

The diagram updates with the calculated values, giving you a visual representation of the landscape slope.

How to Calculate Slope Percentage

You can calculate slope percentage using the rise and run values.

Use this formula:

• Slope (%) = (Rise ÷ Run) × 100

For a rise of 5 m and a run of 20 m:

• Slope (%) = (5 ÷ 20) × 100 = 25%

Therefore, the slope is 25%.

A higher percentage indicates a steeper slope, while a lower percentage represents a gentler slope.

When planning a patio or walkway, you can use the calculator to determine the slope for pavers.

Can Slope Percentage Be Greater Than 100%?

Yes. A slope can be greater than 100% when the rise is larger than the run.

For example, with a rise of 15 m and a run of 10 m:

• Slope (%) = (15 ÷ 10) × 100 = 150%

A 100% slope has equal rise and run. Any slope with a greater rise than run will have a percentage above 100%.

How Do You Convert Slope Percentage to Angle (Degrees)?

Slope percentage and slope angle describe the same slope in different forms. Percentage compares rise with run, while degrees represent the angle between the slope and the horizontal line.

The angle is calculated using:

• Angle = arctan(Rise ÷ Run)

For a rise of 5 m and a run of 20 m:

• Angle = arctan(5 ÷ 20) = arctan(0.25) ≈ 14.04° 

So, a 25% slope has an angle of approximately 14.04 degrees.

How Do You Express Slope as a Ratio?

A slope ratio compares the rise with the run and is often written as 1:n, where 1 represents the rise and n represents the horizontal distance.

For a rise of 5 m and a run of 20 m:

• 5: 20

Divide both values by 5:

• 1: 4

Therefore, the slope ratio is 1:4. This means the surface rises 1 unit for every 4 units of horizontal distance.

The calculator also provides quick examples such as 1:20 = 5%, 1:12 = 8.33%, 1:10 = 10%, 1:8 = 12.5%, and 1:4 = 25% to help you understand common slope ratios.

How Do You Calculate Slope Length?

Slope length is the distance measured along the inclined surface. It can be calculated from the rise and run using the Pythagorean theorem.

• Slope length = √(Rise² + Run²)

For a rise of 5 m and a run of 20 m:

• Slope length = √(5² + 20²) = √425 ≈ 20.6155 m

The calculator performs this calculation automatically, so you do not need to calculate the slope length separately.

If you want to start a new calculation, click Reset to clear the current values and enter new measurements.

Frequently Asked Questions

What is negative slope?

A negative slope indicates that a line falls from left to right on a graph. Picture the line going downhill.

Is slope percentage the same as slope angle?

No. Slope percentage and slope angle describe the same slope using different measurements. Slope percentage is based on the rise and run, while slope angle is measured in degrees.

Can I use different units for rise and run?

Rise and run should use the same unit to calculate the slope. For example, convert feet to meters if necessary instead of combining feet and meters directly.

What is a zero slope?

A zero slope means the line is completely flat and horizontal, with no vertical change from left to right.

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