Braillito Maps · Accessibility guides
ADA curb ramp requirements: slope, width, flares and landing
A curb ramp is the short slope that takes a sidewalk down to the street. The 2010 ADA Standards define it as “a short ramp cutting through a curb or built up to it” (2010 ADA Standards, definition of “curb ramp”). For someone in a wheelchair, pushing a stroller or walking with a cane, it decides whether a corner can be crossed at all. Section 406 of the Standards sets how a curb ramp is built: its slopes, its width, its flared sides, the landing at the top and its position at a crossing. These are those requirements, each with its section, and how they compare with the newer guidelines for sidewalks and streets.
This is a summary. The official 2010 ADA Standards for Accessible Design are the reference.
When a curb ramp is required
Where a floor or ground surface changes level by more than 1/2 inch (13 mm), the change has to be ramped, as a ramp under section 405 or a curb ramp under section 406 (2010 ADA Standards, 303.4). Curb ramps are one of the parts an accessible route can be made of; their flared sides are not (2010 ADA Standards, 402.2). That matters on site: the route is the ramp itself, and the flares serve the people who cross its sides, which is where PROWAG, the guidelines for sidewalks and streets, requires them (PROWAG, R304.2.6). For the sidewalk the curb ramp starts from, see ADA sidewalk requirements.
For state and local governments, the Title II regulation adds a rule about streets. Newly built or altered streets, roads and highways must have curb ramps or other sloped areas at any intersection with curbs or other barriers to entry from a pedestrian walkway, and newly built or altered walkways must have them where they meet streets (2010 ADA Standards, 28 CFR 35.151(i)). Section 406 itself is not limited to streets: it covers curb ramps on any accessible route (2010 ADA Standards, 406.1), and an advisory note deals with built-up curb ramps next to accessible parking spaces (2010 ADA Standards, advisory 502.4). What else Title II asks of state and local governments, from the transition plan to parks and websites, is in ADA Title II.
Section 406.1 says which rules a curb ramp follows: the rules of section 406 itself, plus 405.2 through 405.5 and 405.10 of the ramp section (2010 ADA Standards, 406.1). The list leaves out 405.6 to 405.9, so the 30-inch limit on rise, the 60-inch landings, the handrails and the edge protection of ordinary ramps are not among the rules it applies. For ramps in general, see ADA ramp slope.
Curb ramp slope: running slope, cross slope and counter slope
| Slope | Requirement | Section |
|---|---|---|
| Running slope, along the ramp | 1:12 maximum, 1 inch of rise for every 12 inches of length | 2010 ADA Standards, 405.2 and 406.1 |
| Cross slope, across the ramp | 1:48 maximum | 2010 ADA Standards, 405.3 and 406.1 |
| Counter slope of the gutter and road at the foot of the ramp | 1:20 maximum | 2010 ADA Standards, 406.2 |
| Flared sides | 1:10 maximum, where flares are provided | 2010 ADA Standards, 406.3 |
| Transitions to walks, gutters and streets | at the same level: no lip | 2010 ADA Standards, 406.2 |
In percent, the limits are about 8.3 % for the running slope, 2.1 % for the cross slope, 5 % for the counter slope and 10 % for the flares, the same figures PROWAG prints next to its ratios (PROWAG, R304.2.1, R304.2.2, R304.4.1 and R304.2.6). A 6-inch curb at 1:12 needs a ramp at least 72 inches (6 feet) long; the ADA ramp calculator works out the length for any rise.
The counter slope is the one people forget. The gutter at the bottom of the ramp tilts back the other way, so a wheelchair rolling off the ramp meets a valley; Figure 406.2 shows the ramp at 1:12 meeting a gutter at no more than 1:20 (2010 ADA Standards, Figure 406.2). Where the two slopes are too steep, footrests can catch the ground or the chair can tip forward. The Standards also require the surfaces to meet flush at the bottom (2010 ADA Standards, 406.2): a lip that a walker can step over can stop a small front caster.
In an existing site where space is limited, section 405.2, which 406.1 sends curb ramps to, allows steeper slopes for short rises: up to 1:10 for a rise of 6 inches (150 mm) at most and up to 1:8 for 3 inches (75 mm) at most. Nothing steeper than 1:8 is allowed (2010 ADA Standards, 405.2 and Table 405.2).
Width and surface
- Width: at least 36 inches (915 mm) of clear width (2010 ADA Standards, 405.5 and 406.1). The flared sides do not count, since they are not part of the accessible route (2010 ADA Standards, 402.2).
- Surface: stable, firm and slip resistant, with no changes in level on the ramp other than its running slope and cross slope (2010 ADA Standards, 302.1, 405.4 and 406.1).
- Grates and gaps: openings in the surface may not let a sphere more than 1/2 inch (13 mm) across pass through, and long openings run perpendicular to the main direction of travel (2010 ADA Standards, 302.3), so a drain grate near a ramp does not catch a wheel or a cane tip.
- Water: landings exposed to rain are designed so that water does not collect on them (2010 ADA Standards, 405.10 and 406.1). A puddle at the foot of a ramp hides the edge of the gutter and freezes in winter.
Flared sides and where a curb ramp can go
Flares are the triangles that slope down on either side of many curb ramps. Where a ramp has them, they are no steeper than 1:10 (2010 ADA Standards, 406.3); Figure 406.3 shows that slope measured at the curb face (2010 ADA Standards, Figure 406.3). The rule says “where provided”, so a ramp with returned curbs, square sides instead of flares, has no flare slope to meet (2010 ADA Standards, 406.3).
Neither the ramp nor its flares may project into vehicle traffic lanes, parking spaces or parking access aisles (2010 ADA Standards, 406.5). The advisory to section 502.4 explains why for parking: access aisles have to be nearly level for a wheelchair transfer, and a built-up curb ramp inside one would create slopes steeper than 1:48 (2010 ADA Standards, advisory 502.4). At a marked crossing, the ramp itself sits wholly within the crosswalk markings; only the flares may fall outside them (2010 ADA Standards, 406.5).
The landing at the top of a curb ramp
Every curb ramp has a landing at the top: at least 36 inches (915 mm) long and at least as wide as the ramp leading to it, not counting the flares (2010 ADA Standards, 406.4). It is the place where a wheelchair user turns from the sidewalk onto the ramp. Figure 406.4 shows the 36 inches measured in the direction of the ramp run (2010 ADA Standards, Figure 406.4). Section 406.4 sets the length and width of the landing, not its slope (2010 ADA Standards, 406.4). Where the landing is part of an accessible route, the slope rules for walking surfaces apply: 1:20 at most along the direction of travel and 1:48 at most across it (2010 ADA Standards, 403.1 and 403.3).
On a narrow sidewalk there is sometimes no room for it. In alterations, where there is no landing at the top, the ramp has flares, and those flares are no steeper than 1:12 instead of 1:10 (2010 ADA Standards, 406.4, exception). The gentler flares let someone approach the ramp from the side.
Diagonal curb ramps and islands
| Element | Requirement | Section |
|---|---|---|
| Diagonal ramp edges | where the ramp has returned curbs or other well-defined edges, the edges are parallel to the direction of pedestrian flow | 2010 ADA Standards, 406.6 |
| Clear space at the bottom | at least 48 inches (1220 mm), outside active traffic lanes; at a marked crossing, within the markings | 2010 ADA Standards, 406.6 |
| Curb segments | a diagonal ramp with flares has a segment of curb at least 24 inches (610 mm) long on each side, within the marked crossing | 2010 ADA Standards, 406.6 |
| Raised islands | cut through level with the street, or with curb ramps at both sides | 2010 ADA Standards, 406.7 |
| Level area on an island | at least 48 inches (1220 mm) long by 36 inches (915 mm) wide at the top of each curb ramp, its length in the direction of the ramp’s running slope; it may overlap the accessible route | 2010 ADA Standards, 406.7 |
A diagonal ramp, a single ramp at the corner of an intersection, sends people out toward the middle of the intersection rather than straight into one crosswalk. The 48 inches of clear space at its foot is what keeps a wheelchair user out of moving traffic while turning toward the crossing (2010 ADA Standards, 406.6).
Detectable warnings at curb ramps
A detectable warning is a standard surface built into or applied to a walking surface to warn of a hazard on a circulation path (2010 ADA Standards, definition of “detectable warning”). In the 2010 Standards it is a surface of truncated domes, 0.2 inch (5.1 mm) high and 1.6 to 2.4 inches (41–61 mm) apart center to center, that contrasts with the pavement next to it (2010 ADA Standards, 705.1 to 705.1.3). The full dome measurements, what the domes mean underfoot and the UK tactile paving surfaces are in truncated domes and tactile paving.
Section 406 itself does not mention detectable warnings, and in the 2010 Standards the place that requires them is the edge of rail boarding platforms not protected by screens or guards (2010 ADA Standards, 810.5.2 and 705.2).
PROWAG, the U.S. Access Board’s guidelines for sidewalks and streets, does require them on curb ramps, and becomes enforceable as agencies adopt it as a standard (PROWAG). Curb ramps at crosswalks have a detectable warning surface (PROWAG, R205.2.1) at least 24 inches (610 mm) deep in the direction of travel and across the full width of the ramp run, flares excluded (PROWAG, R305.1.4). Curb ramps used only to connect passenger loading zones, accessible parallel on-street parking spaces, or the access aisles of perpendicular and angled parking spaces to the pedestrian access route do not need one (PROWAG, R205.2, exception). PROWAG keeps the same dome size and spacing as section 705 (PROWAG, R305.1.1 and R305.1.2).
Curb ramps and blended transitions in PROWAG
The Access Board published PROWAG as a final rule on August 8, 2023. The guidelines become enforceable when agencies such as the Department of Justice and the Department of Transportation adopt them as standards; the Department of Transportation adopted them on December 18, 2024 as part of its ADA standards for new construction and alterations of transit stops in the public right-of-way (PROWAG).
PROWAG names two kinds of curb ramp, perpendicular ramps, whose running slope is perpendicular to the curb, and parallel ramps, whose running slope runs along the curb down to a landing at the bottom, and a third way down to the street, the blended transition, with a running slope of 1:20 or less (PROWAG, R304.2 to R304.4). Where PROWAG and section 406 differ:
| Requirement | 2010 ADA Standards | PROWAG |
|---|---|---|
| Width | 36 inches (915 mm) minimum (2010 ADA Standards, 405.5) | 48 inches (1220 mm) minimum, flares excluded; on a shared use path, the width of the path (PROWAG, R304.5.1) |
| Running slope | 1:12 maximum (2010 ADA Standards, 405.2) | 1:12 maximum; where reaching 1:12 would take more than 15 feet (4.6 m), the ramp may be steeper as long as it is at least 15 feet long (PROWAG, R304.2.1, exception) |
| Foot of the ramp | counter slope 1:20 maximum (2010 ADA Standards, 406.2) | change of grade 13.3 % at most, or a transitional space 24 inches (610 mm) long with a running slope of 1:48 at most (PROWAG, R304.5.2) |
| Landing | at the top, 36 inches (915 mm) long (2010 ADA Standards, 406.4) | 48 by 48 inches (1220 × 1220 mm): at the top of a perpendicular ramp when people turn to reach it, at the bottom of a parallel ramp (PROWAG, R304.2.5 and R304.3.4) |
| Space at the bottom | 48 inches (1220 mm) at a diagonal ramp (2010 ADA Standards, 406.6) | 48 by 48 inches (1220 × 1220 mm) beyond a perpendicular ramp, within the crosswalk and outside the travel and bike lanes parallel to it (PROWAG, R304.2.4) |
| How many ramps | section 406 sets no number; under Title II, new or altered streets have curb ramps or other sloped areas at intersections (2010 ADA Standards, 28 CFR 35.151(i)) | one curb ramp or blended transition for each crosswalk at a corner; in alterations, one ramp at the apex where that is technically infeasible (PROWAG, R203.6.1.1) |
| Detectable warnings | not in section 406 (2010 ADA Standards, 406) | required at crosswalks (PROWAG, R205.2.1) |
How to check a curb ramp on site
A tape measure and a level, or a phone app that reads slope in percent, are enough for a first look. It does not replace a survey, but it tells you whether a corner will work:
- Running slope. Lay the level along the ramp: 8.3 % (1:12) at most (2010 ADA Standards, 405.2).
- Cross slope. Turn the level across the ramp: about 2 % (1:48) at most (2010 ADA Standards, 405.3).
- Width. Measure the ramp run between the flares: 36 inches at least (2010 ADA Standards, 405.5).
- Flares. Measure their slope at the curb face: 10 % (1:10) at most (2010 ADA Standards, 406.3).
- Top landing. At least 36 inches (915 mm) long behind the ramp, as wide as the ramp, flares excluded (2010 ADA Standards, 406.4).
- The bottom. No lip where the ramp meets the gutter, and a gutter no steeper than 5 % (1:20) (2010 ADA Standards, 406.2).
- Position. At a marked crossing, the ramp lies inside the crosswalk lines, and nothing sticks out into traffic or a parking space (2010 ADA Standards, 406.5).
- Domes. If there is a warning surface, check that it contrasts with the pavement and still has its domes (2010 ADA Standards, 705.1.3).
Curb ramps in Braillito Maps
Braillito Maps is a community map where each place answers ten questions: step-free entrance or ramp, wide doorway, accessible restroom, accessible parking, tactile paving, braille signage, braille menu, audible signals, guide dogs welcome and a quiet environment. Each answer is yes, no or no data, and the place gets a score out of ten, one point for each yes.
A curb ramp is not a question of its own, because the map describes places, not street corners. It shows up in two of the questions. The first, step-free entrance or ramp, asks whether you can get in without steps; a curb ramp from the parking lot to the door is part of that answer. Tactile paving asks whether there is a tactile guide on the floor for cane users, and the domes at the foot of a ramp are tactile paving too.
The app asks you to mark only what you saw and to leave the rest without data. If the ramp from the parking lot ends in a lip or a steep gutter, that is worth knowing before you mark the entrance. Meet Braillito Maps.
Frequently asked questions
What are the ADA curb ramp requirements?
A running slope of 1:12 at most, a cross slope of 1:48 at most, at least 36 inches (915 mm) of width, flares no steeper than 1:10, a landing at the top at least 36 inches long, a counter slope of 1:20 at most at the gutter, and a flush transition to the street (2010 ADA Standards, 405.2, 405.3, 405.5 and 406.2 to 406.4).
What is the maximum slope of an ADA curb ramp?
1:12, about 8.3 %, along the ramp, and 1:48 across it. The flared sides may be up to 1:10 (2010 ADA Standards, 405.2, 405.3 and 406.3).
How wide does an ADA curb ramp have to be?
At least 36 inches (915 mm) under the 2010 ADA Standards, flares excluded (2010 ADA Standards, 405.5 and 402.2). PROWAG, for sidewalks and streets, asks for 48 inches (1220 mm) and becomes enforceable as agencies adopt it (PROWAG, R304.5.1.1; PROWAG).
Does an ADA curb ramp need a landing?
Yes, at the top: at least 36 inches (915 mm) long and as wide as the ramp. In alterations where there is no room for one, the flares are no steeper than 1:12 (2010 ADA Standards, 406.4).
Do ADA curb ramps need detectable warnings?
Section 406 of the 2010 Standards does not require them; the Standards require detectable warnings at unprotected rail platform edges (2010 ADA Standards, 810.5.2). PROWAG requires them on curb ramps at crosswalks, 24 inches (610 mm) deep and as wide as the ramp, and becomes enforceable as agencies adopt it (PROWAG, R205.2.1 and R305.1.4; PROWAG). The dome measurements are in truncated domes and tactile paving.
Do curb ramps need handrails?
Section 406.1 sends curb ramps to 405.2 through 405.5 and 405.10, not to 405.8, the handrail rule for ramps (2010 ADA Standards, 406.1).
More accessibility guides
- ADA ramp slope: the 1:12 rule, width, landings, handrails and edge protection.
- ADA sidewalk requirements: clear width, passing spaces, grade, cross slope, surface, protruding objects and street furniture, on public sidewalks and on site.
- Truncated domes and tactile paving: what the bumps on curb ramps and platform edges mean, and their sizes in the US and the UK.
- Accessible pedestrian signals: how the push button, the locator tone, the walk tick and the vibrating arrow tell blind pedestrians when to cross.
- Accessible parking: ADA parking requirements: how many spaces, how wide, the access aisle and the sign.
- ADA compliance: a checklist for small businesses, with the 2010 Standards section behind each item.
- ADA Title II: what state and local governments have to make accessible: existing buildings, new construction, streets and curb ramps, parks, programs and the 2024 web rule.
- 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.
- Public Right-of-Way Accessibility Guidelines (PROWAG). U.S. Access Board, final rule published August 8, 2023.
Braillito Maps
Find places with ramps, accessible toilets or tactile paving near you in Braillito Maps
In Braillito Maps, every place answers ten questions. One is the ramp: whether you can get in without steps, by ramp or at street level. It is built by the people who need it, and every place gets a score out of ten.
Free · No ads · For iPhone