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ADA ramp slope: the 1:12 rule, width, landings and handrails
Under the 2010 ADA Standards, a ramp on an accessible route can rise no more than 1 inch for every 12 inches of length. That 1:12 rule is the best-known number, but a ramp also has limits on width, rise per run, landings, handrails and edges. Here they are, with the section of the standard for each.
This is a summary. The official 2010 ADA Standards for Accessible Design are the reference.
The 1:12 rule
Ramp runs can have a running slope no steeper than 1:12, about 8.33 % (2010 ADA Standards, 405.2). A walking surface counts as a ramp once its slope is steeper than 1:20, or 5 % (2010 ADA Standards, definition of “ramp”). For sidewalks, see ADA sidewalk requirements.
To find the length a ramp needs, multiply the rise by 12, or let the ADA ramp calculator do it, landings included:
- a 6-inch step needs at least 72 inches (6 feet) of ramp run;
- an 18-inch rise needs at least 216 inches (18 feet);
- a 30-inch rise, the most a single run may climb, needs at least 360 inches (30 feet).
The cross slope, across the direction of travel, can be no steeper than 1:48 (2010 ADA Standards, 405.3).
Width, rise and landings
| Element | Requirement | Section |
|---|---|---|
| Clear width | 36 inches (915 mm), measured between handrails where they are provided | 2010 ADA Standards, 405.5 |
| Rise per run | 30 inches (760 mm) maximum | 2010 ADA Standards, 405.6 |
| Landings | at the top and bottom of every run; as wide as the widest run and at least 60 inches (1525 mm) long | 2010 ADA Standards, 405.7 |
| Change of direction | a landing at least 60 by 60 inches (1525 × 1525 mm) | 2010 ADA Standards, 405.7.4 |
| Surface | stable, firm and slip resistant; no changes in level on the run | 2010 ADA Standards, 405.4 and 302.1 |
| Wet conditions | landings designed so water does not collect | 2010 ADA Standards, 405.10 |
Handrails and edge protection
- Ramp runs that rise more than 6 inches (150 mm) need handrails (2010 ADA Standards, 405.8).
- The top of the gripping surface is 34 to 38 inches (865–965 mm) above the ramp surface, at a consistent height (2010 ADA Standards, 505.4).
- Handrails extend horizontally at least 12 inches (305 mm) beyond the top and bottom of each run (2010 ADA Standards, 505.10.1).
- Each side of a run and landing needs edge protection: either the surface extends at least 12 inches (305 mm) beyond the inside face of the handrail, or a curb or barrier stops a 4-inch (100 mm) sphere from slipping through near the surface (2010 ADA Standards, 405.9).
The diameter of the rail, its clearance from the wall, the handrails on stairs and how to check one on site are in ADA handrail requirements.
Existing buildings and curb ramps
In existing sites and buildings where space is limited, a steeper ramp is allowed for short rises: steeper than 1:12 but no steeper than 1:10 for a rise of up to 6 inches (150 mm), and steeper than 1:10 but no steeper than 1:8 for up to 3 inches (75 mm). Nothing steeper than 1:8 is allowed (2010 ADA Standards, table 405.2).
Curb ramps follow the same running slope, cross slope and width rules; their flared sides can be no steeper than 1:10 and they need a 36-inch (915 mm) landing at the top (2010 ADA Standards, 406.1, 406.3 and 406.4). The two kinds of curb ramp, the landings, the flares and the detectable warnings are in ADA curb ramp requirements.
The standard’s own advice is to use the least possible slope and, where possible, add stairs next to the ramp for people who find distance harder than steps (2010 ADA Standards, advisory 405.2).
Frequently asked questions
What is the ADA ramp slope?
1:12 at most, meaning 1 inch of rise for every 12 inches of run, about 8.33 % (2010 ADA Standards, 405.2).
How long does a ramp need to be?
At least 12 times the rise: 72 inches (6 feet) for a 6-inch rise and 360 inches (30 feet) for a 30-inch rise, which is the most one run may climb before a landing. The ADA ramp calculator works it out for any rise.
When does an ADA ramp need handrails?
When a run rises more than 6 inches (150 mm). The handrails are 34 to 38 inches (865–965 mm) high (2010 ADA Standards, 405.8 and 505.4).
How wide must an ADA ramp be?
At least 36 inches (915 mm) of clear width, measured between handrails where there are handrails (2010 ADA Standards, 405.5).
How often does an ADA ramp need a landing?
At the top and bottom of every run, and a run can rise 30 inches (760 mm) at most; landings are at least 60 inches (1525 mm) long (2010 ADA Standards, 405.6 and 405.7).
More accessibility guides
- ADA handrail requirements: handrail height, diameter, clearance from the wall and the extensions at ramps and stairs.
- ADA curb ramps: curb ramp slope, counter slope, width, flared sides, the top landing, diagonal ramps, islands and detectable warnings.
- ADA door width: 32 inches of clear width, maneuvering space, thresholds, hardware and opening force.
- ADA compliance: a checklist for small businesses, with the 2010 Standards section behind each item.
- Accessible parking: ADA parking requirements: how many spaces, how wide, the access aisle and the sign.
- ADA platform lifts: where a wheelchair lift may replace a ramp or an elevator, platform size, doors and gates, controls and use without an attendant.
- All accessibility guides
Sources
Every figure in this guide comes from one of these official texts, which we read in October 2026.
- 2010 ADA Standards for Accessible Design. U.S. Department of Justice, published September 15, 2010; required for new work since March 15, 2012.
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