Percentage and degrees
Convert slope percentage to degrees or calculate it from rise and horizontal run.
Slope Calculator for Percentage and Degrees
Calculate slope from rise and horizontal run, or enter a percentage, angle or 1:X ratio. Get all equivalent values and the inclined length.
1:X ratio
Calculate the horizontal distance corresponding to each unit of vertical rise.
Inclined length
Calculate the actual distance between the start and end points.
Free online tool
Slope Calculator
Calculate slope in percent, degrees and 1:X ratio from rise and horizontal run.
Slope information
Enter rise as a positive value. The result represents the slope magnitude.
Results are approximate. Drainage, ramps, accessibility, roads, roofs and structural projects must comply with the minimum or maximum slopes required by applicable regulations and technical specifications.
How to calculate a slope
Slope expresses the relationship between a change in elevation and a distance measured horizontally.
To calculate slope as a percentage, divide the vertical rise by the horizontal run and multiply by 100.
The angle is obtained by applying the arctangent function to the relationship between rise and horizontal run.
Slope percentage
Slope (%) = rise ÷ horizontal run × 100
Inclined length
Length = √(horizontal² + rise²)
Slope percentage, degrees and 1:X ratio
5%
≈ 2.86° · 1:20
10%
≈ 5.71° · 1:10
12.5%
≈ 7.13° · 1:8
20%
≈ 11.31° · 1:5
Slope example using rise and horizontal run
Known values
Horizontal run8 m
Vertical rise0.40 m
DirectionAscending or descending
Result
The slope percentage is:
0.40 ÷ 8 × 100 = 5%
A 5% slope is equivalent to an approximate ratio of:
1:20
The corresponding angle is approximately 2.86°.
The inclined length is approximately 8.01 meters.
Terrain slopes
In surveying, slope describes the inclination between two points on the terrain.
It can be used to interpret surveys, design platforms, estimate cuts and fills or analyze routes.
Construction work should be based on levels and coordinates obtained from an appropriate land survey.
Ramps, drainage and roofs
Ramp slopes depend on length, intended use and accessibility requirements.
Drainage systems need sufficient slope to move water without creating stagnant areas.
Roof slopes must be compatible with the material, overlaps and rainwater drainage system.
Percentage, degrees and 1:X ratio
These three expressions represent the same inclination but are used differently depending on the discipline and technical document.
Percentages are common for ramps and drainage, degrees describe angles and the 1:X ratio indicates the horizontal run required for each unit of vertical rise.
Technical verification
A mathematically calculated slope is not automatically suitable for a project.
Applicable regulations, materials, safety, drainage, accessibility and project drawings must be checked.
Slopes in Panama construction projects
In Panama, rainwater management and terrain analysis are important because of local rainfall and humidity conditions.
Slopes for internal roads, platforms, roofs, gutters, ramps and drainage should be coordinated with surveying, architecture and building services.
Visit MG Architecture & EngineeringSlope and rise questions
How is slope percentage calculated?
Divide the vertical rise by the horizontal run and multiply the result by 100.
What does a 10% slope mean?
It means there are 10 units of vertical rise for every 100 units of horizontal run. For example, a 5-meter run would have a rise of 0.5 meters.
How many degrees is a 5% slope?
A 5% slope is approximately 2.86 degrees and is equivalent to a 1:20 ratio.
How do I convert slope percentage to degrees?
Calculate the arctangent of the slope percentage divided by 100. A 10% slope is approximately equal to 5.71 degrees.
What does a 1:20 slope mean?
It means there is one unit of vertical rise for every 20 units of horizontal distance. A 1:20 ratio is equal to a 5% slope.
Are slope and angle the same?
Not exactly. Slope expresses the relationship between rise and horizontal run, while angle expresses the inclination in degrees.
How do I calculate rise from a slope percentage?
Multiply the horizontal run by the slope percentage divided by 100.
How is inclined length calculated?
Use the Pythagorean theorem. Inclined length is the square root of the horizontal run squared plus the vertical rise squared.
Can the calculator be used for descending slopes?
The calculator uses positive values and returns the slope magnitude. Whether the slope rises or falls depends on the project direction.
Can this tool be used for ramps and accessibility?
It can be used to check mathematical equivalences and preliminary values, but the permitted slope must be verified against applicable accessibility requirements and project specifications.
Can this tool be used for drainage and roofs?
Yes, as a mathematical calculator. Required minimum or maximum slopes must follow the drainage system, roof material, technical specifications and project conditions.