ADA Ramp Calculator
Enter your total rise and target slope to get the ramp length, run, number of switchback runs and landings, and clear width — each checked against the ADA §405 accessibility limits.
Vertical height the ramp must climb.
Clear width between the handrails (ADA minimum 36″).
1:12 — 8.3% grade. ADA caps the maximum at 1:12; 1:16 is comfortable and 1:20 is the gentlest before it is just a walk.
Ramp length (sloped)
30' 5/16"
9.152 m
Horizontal run
29' 11 1/16"
9.12 m
Slope
1:12
8.3% grade
Ramp runs
1
0 landings
Rise per run
29 15/16"
760 mm
Footprint w/ landings
29' 11 1/16"
9.12 m
Running slope 1:12 (8.3%) meets the ADA §405.2 maximum of 1:12; 1:16 or gentler is more comfortable.
The 2' 5 15/16" rise fits in one run — ADA §405.6 allows up to 30″ (762 mm) before a landing is required.
No intermediate landing is needed — a top and bottom landing still apply per ADA §405.7.
Clear width 3' 6" meets the ADA §405.5 minimum of 36″ (915 mm) between handrails.
ADA ramp slope and length (§405.2)
The single most important ramp number is the running slope. The 2010 ADA Standards for Accessible Design, §405.2, set the steepest a ramp run may be at 1:12 — 1″ of rise for every 12″ of run, an 8.33% grade. Because the run is the rise times the slope ratio, the length grows fast: a 30″ rise at 1:12 needs a 30 ft run. The calculator multiplies your rise by the ratio you pick, so you can see the trade-off between a steeper, shorter ramp and a gentler one.
A 1:16 slope is widely recommended as more comfortable to push, and anything 1:20 or gentler is treated as a walking surface rather than a ramp — it no longer needs ramp handrails or landings. Aim for 1:16 where you have the room; reserve 1:12 for tight retrofits.
Runs, landings and width (§405.6, §405.7, §405.5)
A single ramp run may rise at most 30″ before a level landing is required (§405.6). For taller rises Stairs Calc splits the climb into equal runs separated by landings, so each run stays under the limit. Each intermediate landing must be at least 60″ long in the direction of travel and at least as wide as the ramp run leading to it (§405.7); a landing where the ramp changes direction needs a larger turning space.
The clear width between the handrails must be at least 36″ (§405.5). A green check means the dimension passes; a red mark means it does not, so you can lengthen the ramp or widen it before you build. To size the rail itself, the handrail length calculator gives the sloped grip run plus the code end extensions, and the stairs with landing calculator lays out the level landings between flights.
Frequently asked questions
What is the maximum slope for an ADA ramp?
The steepest a ramp run may be is 1:12 — 1″ of rise for every 12″ of run, an 8.33% grade (ADA §405.2). A 1:16 slope is more comfortable, and anything 1:20 or gentler is treated as a walking surface rather than a ramp.
How long does a wheelchair ramp need to be?
At the 1:12 maximum slope the run is 12 times the rise, so a 6″ rise needs 6 ft of ramp and a 30″ rise needs 30 ft. Stairs Calc multiplies your rise by the chosen slope ratio to give the exact run and sloped length.
How much rise can a single ramp run have before a landing?
A single ramp run may rise at most 30″ before a level landing is required (ADA §405.6). Stairs Calc splits a taller rise into equal runs and counts the landings between them.
How big does an ADA ramp landing have to be?
A landing must be at least 60″ long in the direction of travel and at least as wide as the widest ramp run leading to it (ADA §405.7), with a larger turning space where the ramp changes direction.
How wide does a wheelchair ramp have to be?
The clear width between the handrails must be at least 36″ (ADA §405.5). Stairs Calc flags your width against that minimum as you change it.
Related stair calculators
Written by the Stairs Calc editorial team. Methodology and code references: see our methodology.
Built and maintained by builders, drafters and engineers who plan stairs for a living — every code limit is transcribed from the published standard and cited to its exact section.
Last reviewed 2026-06-20 against IRC 2021/2024
Stairs Calc gives accurate geometry and checks it against published building-code limits, but results are estimates for planning. Codes are adopted and amended locally and change over time. Always confirm dimensions against your local adopted code and a licensed professional before you build.