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A threshold ramp is a short, sloped piece that bridges the small step at a doorway or other low change in floor level so that wheels, walkers and feet can cross it. This guide is general information, not medical, legal or building-code advice. It explains how the U.S. ADA Accessibility Standards treat small level changes, what the numbers are, and where a threshold ramp sits in that picture.
Short answer
A threshold ramp fills in a low step, typically at a door. Under the ADA Accessibility Standards, a change in level above 1/2 inch must be ramped, a doorway threshold may be 1/2 inch high at most, and changes between 1/4 and 1/2 inch must be beveled no steeper than 1:2. The Standards govern facilities; they are not a specification for any particular product.
Definition and scope
“Threshold ramp” describes a function rather than a single product type. It is a small incline that lets a wheeled device or a person with limited stepping ability cross a raised door sill or a similar low change in level. It is distinct from a full-length ramp that connects two floor levels, which the Standards cover separately. People searching the term are usually dealing with a sliding-door track, a door sill, or a step at the edge of a room, and the most useful first question is how tall that change in level is.
It is also a different object from a walking aid or a wheelchair. For those, see the plain-language guides on wheelchairs, walkers and canes, and the general explainer on what counts as a medical device.
How the ADA Standards treat small changes in level
The U.S. Access Board publishes the ADA Accessibility Standards. Section 303 covers changes in level on accessible routes, and section 404.2.5 covers thresholds at doorways. Read together, they set out a height ladder.
| Height of the change in level | What the Standards say | Section |
|---|---|---|
| Up to 1/4 inch (6.4 mm) | May be vertical | 303.2 |
| Over 1/4 inch up to 1/2 inch (13 mm) | Must be beveled with a slope not steeper than 1:2 | 303.3 |
| Greater than 1/2 inch | Must be ramped and comply with the ramp requirements | 303.4, 405 |
| Doorway threshold, if provided | 1/2 inch high maximum; raised thresholds must also comply with 302 and 303 | 404.2.5 |
The Access Board’s advisory to 303.3 adds that a 1/2 inch change may be made up of 1/4 inch vertical plus 1/4 inch beveled, but the combined change may never exceed 1/2 inch. Section 404.2.5 also contains an exception: existing or altered thresholds up to 3/4 inch high that have a beveled edge on each side, no steeper than 1:2, are not required to comply with the 1/2 inch limit.
The practical reading is that a threshold ramp is one way to meet the bevel-or-ramp rule at a doorway. It is not a separate legal category with its own height table.
A worked example, from the stated slopes
The figures below are arithmetic from the slopes quoted above, not advice about any real doorway.
- A slope of 1:2 means 1 unit of rise for every 2 units of run. A 1/2 inch change beveled at 1:2 therefore takes 1 inch of run.
- A 3/4 inch raised threshold is above the 1/2 inch figure, so section 303 says the change in level must be ramped. Section 405.2 gives a running slope not steeper than 1:12 for ramp runs, so 3/4 inch of rise at 1:12 works out to 9 inches of run.
- Under the existing-or-altered exception in 404.2.5, a 3/4 inch threshold with a 1:2 bevel on each side would have 1 1/2 inches of run on each side.
The comparison shows why the same step can be treated differently depending on whether the facility is new, existing or altered, and why the answer should come from the facility’s own accessibility review rather than a rule of thumb.
Where it matters for labs, clinics and supply decisions
Doorways on routes used by wheelchairs, walkers and carts are where this rule is applied in practice. The Standards put the 1/2 inch limit on doorway thresholds, and anything above 1/2 inch must be ramped, so a facilities review of a raised sill starts with measuring its height against the table above.
The Job Accommodation Network (JAN) lists a rubber threshold ramp in its accommodation product entries. The listing describes a recycled-rubber ramp with tapered edges and a molded slip-resistant surface, used for thresholds up to 2 1/2 inches, and says it suits sliding or tight-fitting doors because it does not cross the threshold. For the mobility devices that cross these thresholds, see the rollator guide and the guide to wheelchair weight categories.
Common misunderstandings
A threshold ramp is the same as a code-compliant ramp
Not necessarily. Ramp runs in section 405 carry a 1:12 maximum running slope, a 1:48 maximum cross slope, and no changes in level within the run other than those slopes. Whether a short, bevel-style piece satisfies the bevel rule or the ramp rule depends on its height and slope. The Standards apply to facilities, not to products, so a product description alone does not show that a doorway complies.
Any step at a door can simply be beveled
Only changes up to 1/2 inch are covered by the beveled option in 303.3. Anything greater than 1/2 inch must be ramped.
The 1:12 figure applies to every small ramp
The 1:12 figure is the stated limit for ramp runs in 405.2, which also has an exception allowing steeper slopes in existing facilities where space is limited. The bevel rule for small changes in level in 303.3 uses 1:2.
The ADA Standards are a product specification
They are design requirements for facilities and elements such as doorways and routes. They do not certify a product.
Frequently asked questions
What is a threshold ramp?
A short incline that bridges a low change in level, such as a door sill, so wheeled devices and people with limited stepping ability can cross it.
How high can a doorway threshold be under the ADA Standards?
Section 404.2.5 sets 1/2 inch as the maximum for a threshold, if one is provided, with a separate exception for existing or altered thresholds up to 3/4 inch that are beveled on each side at no steeper than 1:2.
When must a change in level be ramped?
Section 303.4 says changes in level greater than 1/2 inch must be ramped.
What slope does a ramp run use?
Section 405.2 gives a running slope not steeper than 1:12 for ramp runs.
Sources
- U.S. Access Board, ADA Accessibility Standards, sections 303, 404.2.5 and 405: access-board.gov/ada (checked 30 October 2026).
- Job Accommodation Network, Rubber Threshold Ramp product entry: askjan.org (checked 30 October 2026).
