ADA 2010 §405
ADA ramp slope calculator.
Enter a rise and a slope, and get the ramp length, landings and total footprint — checked line by line against the 2010 ADA Standards, with any failure named.
The vertical height to climb. Units welcome: 24 in, 2 ft, 0.6 m.
1:12 is 8.33%, the ADA maximum. Leave it there to size a compliant ramp.
Common Slopes
A slope of 1:20 or gentler is technically a walkway rather than a ramp, and is not subject to the handrail and landing rules in §405.
Meets ADA §405
- Running slope is within the 1:12 maximum in §405.2.
- Rise is within the 30″ per-run maximum in §405.6.
Other requirements that always apply
Ramp Run
24′ 1/8″
Ratio
1 : 12
Angle
4.76°
Ramp Runs Needed
1
Intermediate Landings
0
Total Footprint
34′ 1/8″
Footprint includes a 60″ landing at each end and one between each pair of runs. It does not include turning space, door manoeuvring clearance, or the guard and handrail extensions.
The Other §405 Rules
Slope is only one requirement. These apply to the same ramp and are just as capable of failing an inspection.
- Cross slope
- 1:48 maximum (2.08%)
- Clear width
- 36″ minimum between handrails
- Rise per run
- 30″ maximum
- Landing length
- 60″ minimum, top and bottom
- Turning landings
- 60″ × 60″ minimum where the ramp changes direction
- Handrails
- Both sides where the rise exceeds 6″
- Edge protection
- Required on each side of ramp runs and landings
- Surface
- Firm, stable and slip resistant
The 1:12 Rule
The 2010 ADA Standards for Accessible Design cap the running slope of a ramp at 1:12 — one unit up for every twelve along. As a percent grade that is 8.33%, and as an angle it is 4.76°. It is the number everyone quotes, and it is a maximum, not a target: a gentler ramp is always acceptable and is markedly easier to use.
Sizing a wheelchair ramp from that rule is straightforward. Multiply the rise by twelve and you have the minimum ramp run. Two feet of rise needs twenty-four feet of ramp. What surprises people is how much room that takes once landings are added — a modest three-step porch quickly needs thirty-odd feet of yard.
Slope Alone Does Not Make a Ramp Compliant
A ramp at exactly 1:12 can still fail inspection on any of half a dozen other counts. The three that catch people out most often:
- The 30-inch rise limit. No single ramp run may climb more than 30 inches. Anything taller has to be split, with a level landing between the runs.
- Cross slope. The slope across the ramp — side to side — is limited to 1:48, about 2.08%. It is easy to build in accidentally when a ramp is poured against an existing grade.
- Landings. Every run needs a level landing at both ends, at least 60 inches long and as wide as the ramp. Where the ramp changes direction, that landing must be at least 60 by 60 inches.
Where the ADA Applies
The ADA governs public accommodations and commercial facilities. A ramp at a private home is covered by local building code instead, which is often less demanding. That said, the 1:12 figure exists because it reflects what a person can actually propel a wheelchair up — so it is worth treating as a design goal even where it is not a legal requirement.
This wheelchair ramp slope calculator checks the geometry described in §405 and reports which rule any given design breaks. It is a design aid, not an inspection, and it does not replace review by a qualified professional or your local code official.
Common Questions
What is the maximum slope for an ADA ramp?
The 2010 ADA Standards §405.2 set a maximum running slope of 1:12 for ramps on an accessible route — one unit of rise for every twelve units of run, which is an 8.33% grade or 4.76°. The cross slope is separately limited to 1:48 under §405.3.
How long does a wheelchair ramp need to be?
At the 1:12 maximum, the ramp run is twelve times the rise. A 24-inch rise needs at least 24 feet of ramp, and a 30-inch rise needs 30 feet. Landings at each end add further length, so the total footprint is always larger than the ramp run alone.
What is the maximum rise for a single ramp run?
30 inches, under §405.6. A greater total rise must be broken into multiple runs with a level landing between each, and each landing must be at least 60 inches long under §405.7.3.
When are handrails required on a ramp?
Handrails are required on both sides of any ramp run with a rise greater than 6 inches, under §405.8. The clear width between them must be at least 36 inches under §405.5.
Do residential ramps have to meet the ADA?
Usually not. The ADA applies to public accommodations and commercial facilities, not private homes, so a residential ramp is governed by local building code instead. The 1:12 figure is still a sensible target, and many builders use it voluntarily because it is genuinely usable.
Is a steeper ramp ever allowed?
Only in specific alteration cases where space is genuinely constrained, and the 2010 Standards limit those exceptions tightly — for example 1:10 for a rise of up to 6 inches. New construction has no such allowance. Treat any steeper slope as non-compliant unless a code official confirms otherwise.