Ramp Calculator
Enter the rise and run to find the ramp's slope percentage, angle, and total length.
How ramp slope is calculated
Slope percentage is the rise divided by the run, multiplied by 100 — an 8.33% slope means the ramp climbs about 8.33 units of height for every 100 units of horizontal distance. This is the same measurement as a 1:12 ratio, commonly cited in accessibility guidelines.
The angle is found using the inverse tangent (arctan) of rise divided by run, while the ramp's actual surface length is found with the Pythagorean theorem: length = √(rise² + run²), treating the rise, run, and ramp surface as a right triangle.
Frequently asked questions
What does a 1:12 ramp ratio mean?
A 1:12 ratio means 1 unit of rise for every 12 units of run — equivalent to about 8.33% slope. This is a commonly referenced maximum slope ratio in accessibility design guidelines for wheelchair ramps, though exact requirements vary by jurisdiction and application.
Why does the ramp length differ from the run?
The run is the horizontal distance only, while the ramp's actual surface is longer since it travels diagonally upward — the difference becomes more noticeable at steeper slopes, where the ramp surface is meaningfully longer than its horizontal footprint.
Is this calculator a substitute for official accessibility code requirements?
No — this calculates the geometry only. Specific slope limits, landing requirements, handrail specifications, and other accessibility code requirements vary by jurisdiction and application, so always check your local building code for compliance.