Gradient Calculator
Convert between angle, %, and 1:N gradient
Features
Convert angle, %, and 1:N at once
Enter any one notation and see all others displayed simultaneously
Calculate from horizontal distance and rise
Calculate gradient and hypotenuse length from two measurements at once
Visualize slope with a right triangle
Triangle slope, angle, and percentage values are drawn to match your input
Copy all notations in one line
Copy all notations in a single-line format ready to paste into estimates or drawings
How to Use
Select input method with tabs
Choose "Convert from notation" or "Calculate from distance" using the tabs at the top
Enter the value you want to convert
For notation: select notation type and enter one value. For distance: enter horizontal distance and rise
Review results and diagram, then copy
Check the results and diagram that appear instantly, then copy by row or use "Copy all results"
Use Cases
Check roof pitch angle
Verify what angle and percentage a roof pitch represents, and use it for roofing or exterior work estimates
Convert road and drainage slope notations
Convert a 2% slope to angle or 1:N notation and standardize expressions in drawings and reports
Check wheelchair ramp slope
Calculate slope from ramp height and length to verify it meets standards like 1:12
Understand hillside or yard slope
Easily determine the angle of a hillside or yard from elevation change and distance
Knowledge Base
Relationship between gradient percentage and angle
Gradient percentage expresses how much the slope rises over a horizontal distance of 100, calculated by multiplying the tangent (tan) of the angle by 100. A 45° slope rises 100 units vertically for every 100 units horizontally, making it 100%, and as the angle approaches 90°, the percentage increases without limit.
- 10% gradient angle：A 10% gradient rises 10 units vertically for every 100 units horizontally, which equals approximately 5.71° in angle.
- Percentage of a 30° gradient：A 30° gradient rises approximately 57.74 units vertically for every 100 units horizontally, making it approximately 57.74%.
What is roof pitch (sun)?
Roof pitch is a notation used in Japanese roofing that expresses slope by how many sun (units) the roof rises over a horizontal distance of 10 sun (1 shaku). A 4-sun pitch rises 4 units vertically for every 10 units horizontally, equivalent to 40% or approximately 21.8°.
- 3-sun pitch：A 3-sun pitch rises 3 units vertically for every 10 units horizontally, equivalent to 30% or approximately 16.7°.
- Right angle pitch (kanekoubai)：A 10-sun pitch has equal horizontal and vertical distances, called right angle pitch, equivalent to 45°.
How to read gradient ratio 1:N
Gradient ratio 1:N expresses a slope where for every 1 unit of vertical rise, there are N units of horizontal distance. Larger N values indicate gentler slopes. To convert 1:N to percentage, divide 100 by N: 1:10 equals 10%, and 1:20 equals 5%.
- Wheelchair ramp 1:12：Wheelchair ramps typically follow a gentler slope than 1:12 (approximately 8.33% or 4.76°) as a guideline.
Safety and Privacy
Runs entirely in your browser
Your input data is processed only within your browser and is never sent externally.
Processing only in your browser
Gradient conversion is processed entirely within your browser, and input data is not sent to any server.
Communications encrypted with HTTPS
Page loading is also encrypted by TLS, and content cannot be read by third parties.
No transmission to third parties
Input content is not sent to external services such as ad networks or trackers.
No automatic saving of results
Numeric values you enter (angle, percentage, distance, etc.) and input suggestions are not stored on the server.
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Updates
- update #331
Slope calculator added: convert between angles, percentages, and 1:N ratios, visualize slope with a diagram