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ADA Ramp Slope Calculator
Enter the total rise to get the required ramp length at the 1:12 ADA maximum, how many runs it breaks into, how many landings you have to fit, the total footprint, and the slope in both percent and degrees.
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Book a DemoCalculate Ramp Length, Landings and Footprint
The rise drives everything else. Enter it once and the calculator works the run, the number of runs, the landings and the space you need on site.
Finished floor or threshold down to finished grade.
1:12 is the ADA ceiling, not a target.
Measured between handrails where present.
📋 Important: All calculator results are ballpark estimates
The figures shown are approximate estimates intended for planning purposes only. They are not a substitute for a design prepared by a qualified professional, a plan review, or the requirements of your local building department. State and local accessibility codes frequently go beyond the federal ADA standard, and site conditions such as drainage, frost depth, door swings and guard requirements change what you can actually build. Always verify against the 2010 ADA Standards and the code in force in your jurisdiction.
How to Size an ADA-Compliant Ramp
Ramp length by rise, at the 1:12 maximum
This is the table most people are actually looking for. Every figure is worked at the 1:12 ADA maximum running slope, with 60-inch landings at the top and bottom of each run and a new run started every 30 inches of rise:
| Total rise | Ramp run at 1:12 | Runs | Landings | Total footprint |
|---|---|---|---|---|
| 6" | 6' | 1 | 2 | 16' |
| 1' | 12' | 1 | 2 | 22' |
| 1' 6" | 18' | 1 | 2 | 28' |
| 2' | 24' | 1 | 2 | 34' |
| 2' 6" | 30' | 1 | 2 | 40' |
| 3' | 36' | 2 | 3 | 51' |
| 4' | 48' | 2 | 3 | 63' |
| 5' | 60' | 2 | 3 | 75' |
| 6' | 72' | 3 | 4 | 92' |
Footprint figures are straight-line. A switchback roughly halves the length and roughly doubles the width, and its turning landing has to be a full 60″ × 60″.
The 1:12 rule, and why it is a ceiling rather than a target
Section 405.2 of the 2010 ADA Standards caps the running slope of a ramp at 1:12 — one inch of rise for every twelve inches of run. That is 8.33 percent, or about 4.76 degrees. It is worth saying plainly that 1:12 is hard work for someone self-propelling a manual wheelchair, particularly on a long run. Where the site has the room, specifying 1:16 or 1:20 produces a ramp people can actually use unassisted. There is a bonus at 1:20: a walking surface sloped at less than 1:20 is not classed as a ramp by the ADA at all, so it escapes the landing, handrail and edge-protection requirements entirely.
Percent and degrees are not interchangeable
This is the single most common error on a ramp submittal. A 1:12 slope is 8.33 percent; it is 4.76 degrees. Setting a laser or a digital level to 8.33 degrees builds a ramp roughly 75 percent steeper than code allows. The conversions:
| Ratio | Percent | Degrees | Status |
|---|---|---|---|
| 1:8 | 12.50% | 7.13° | IRC limit for a residential ramp not serving the egress door |
| 1:12 | 8.33% | 4.76° | ADA maximum running slope (§405.2) |
| 1:16 | 6.25% | 3.58° | Common gentler specification |
| 1:20 | 5.00% | 2.86° | Below this the ADA does not class it as a ramp |
| 1:48 | 2.08% | 1.19° | Maximum cross slope on a ramp or landing (§405.3) |
Landings, runs and the 30-inch rule
Section 405.6 limits a single ramp run to 30 inches of rise. At 1:12 that is a 30-foot run, which is where the “30-foot maximum” you hear on site comes from — but the limit is on the rise, so it applies whichever slope you pick. Anything taller splits into multiple runs with a level landing between each pair. Section 405.7 sets the landing rules: one at the top and one at the bottom of every run, at least 60 inches long and at least as wide as the ramp leading into it, and a full 60 by 60 inches wherever the ramp changes direction. Landings may slope up to 1:48 for drainage and no more. That landing arithmetic is what catches people out on tight sites — a 60-inch rise needs 60 feet of ramp and 15 feet of landings.
Width, handrails and edge protection
The clear width of a ramp run is 36 inches minimum, measured between the handrails where handrails are present (§405.5) — so a 36-inch clear ramp with handrails is wider than 36 inches overall. Handrails are required on both sides of any run with a rise greater than 6 inches (§405.8). Edge protection is required on ramp runs and landings (§405.9) and can be satisfied with a curb at least 4 inches high, a rail or screen that will not pass a 4-inch sphere, or a walking surface that extends at least 12 inches beyond the inside face of the handrail. Landings exposed to weather must be designed so water does not accumulate on them (§405.10).
Residential ramps follow a different code
The ADA applies to places of public accommodation and commercial facilities — it does not govern a private single-family home. Residential work falls under the International Residential Code and your jurisdiction’s amendments to it. Under IRC Section R311.8.1 a ramp serving the required egress door is held to 1:12, while other residential ramps may be as steep as 1:8. Plenty of remodelers build residential ramps to the 1:12 ADA figure anyway, because it is easier to use and it holds up better if the property is later sold or rented. Either way, confirm with the local building department before you pour footings or set posts — accessibility is one of the areas where state and local amendments most often exceed the federal baseline.
Pricing a ramp once you know the geometry
The calculator gives you the geometry; the estimate comes from what that geometry costs to build. Once you have the run length and landing count, take off the deck area, the footings, the handrail runs and the edge protection, then work your labor and margin the way you would on any other scope — the contractor markup calculator converts a cost figure into a sell price, and the concrete calculator handles the pour if the ramp is cast in place rather than framed. Accessibility work is very often a change order on a larger commercial job, which is where commercial contractor software earns its keep: the scope, the approval and the revised contract value all stay attached to the job instead of living in an email thread.
- Measure the rise from finished floor or threshold to finished grade, not to existing grade
- Fit the landings before you commit to a slope — they are what usually breaks a tight site
- Check the door swing at the top landing; a door opening onto a ramp run is a failure
- Hold cross slope to 1:48 or less, on the runs and on the landings
- Confirm state and local amendments before you build — they frequently exceed the ADA
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Book a Free DemoFrequently Asked Questions
What is the ADA maximum ramp slope?
Section 405.2 of the 2010 ADA Standards for Accessible Design sets the maximum running slope of a ramp on an accessible route at 1:12. That means every 1 inch of vertical rise needs at least 12 inches of ramp run — a 1:12 slope is 8.33 percent, or about 4.76 degrees. The 1:12 figure is a ceiling, not a target. A ramp built right at 1:12 is legal but hard work to push a wheelchair up, so designers frequently specify 1:16 or 1:20 where the site allows it. A surface sloped at less than 1:20 is not classed as a ramp by the ADA at all and does not need landings, handrails or edge protection.
How long does a wheelchair ramp need to be?
At the 1:12 ADA maximum, the ramp run is the vertical rise multiplied by 12. A 24-inch rise needs 24 feet of run, a 30-inch rise needs 30 feet, and a 36-inch rise needs 36 feet. That is only the sloped portion — you also have to fit the landings. Every ramp needs a level landing at the top and the bottom, each at least 60 inches long, and any rise over 30 inches has to be split into multiple runs with a 60-inch landing between them. A 36-inch rise therefore needs 36 feet of ramp plus three 60-inch landings, for a total footprint of about 51 feet.
What is the maximum rise for a single ramp run under the ADA?
Section 405.6 limits any single ramp run to a maximum rise of 30 inches. At the 1:12 maximum slope that works out to a 30-foot run, which is where the commonly quoted '30-foot rule' comes from. The limit is on the rise, not the length, so it applies no matter which slope ratio you use. A rise taller than 30 inches has to be broken into two or more runs separated by level landings, and each of those landings adds at least 60 inches to the total footprint.
What are the ADA landing requirements for ramps?
Section 405.7 requires a level landing at the top and the bottom of every ramp run. Each landing must be at least 60 inches long and at least as wide as the ramp run leading into it. Where a ramp changes direction, the landing must be at least 60 inches by 60 inches so a wheelchair can turn. Landings are not perfectly flat in practice — they may slope up to 1:48 in any direction for drainage, and landings exposed to weather have to be designed so water does not pond on them.
When are handrails required on an ADA ramp?
Section 405.8 requires handrails on both sides of any ramp run with a rise greater than 6 inches. Below that threshold no handrails are required. Ramp runs also need edge protection under Section 405.9 — a curb at least 4 inches high, a rail or screen that will not let a 4-inch sphere pass, or a surface that extends at least 12 inches beyond the inside face of the handrail. The minimum clear width of the ramp itself is 36 inches, measured between the handrails where handrails are present.
What slope is a 1:12 ramp in degrees and percent?
A 1:12 slope is 8.33 percent and approximately 4.76 degrees. A 1:16 slope is 6.25 percent and about 3.58 degrees. A 1:20 slope is 5 percent and about 2.86 degrees. To convert any ratio, divide 1 by the run figure for the decimal slope, multiply by 100 for percent, and take the arctangent for degrees. Note that percent and degrees are not interchangeable — an 8.33 percent slope is not an 8.33 degree slope, and confusing the two produces a ramp more than 75 percent steeper than the code allows.
Do ADA ramp rules apply to a private home?
The ADA governs places of public accommodation and commercial facilities, not private single-family residences. Residential ramps fall under the International Residential Code and whatever amendments your jurisdiction has adopted. Under IRC Section R311.8.1, a ramp serving the required egress door is limited to 1:12, while other residential ramps may be as steep as 1:8. Many homeowners and remodelers still build to the 1:12 ADA figure because it is easier to use and holds up better if the property is later sold or rented. Always confirm the requirement with your local building department before you pour or frame.
How much space do I need for a ramp with a 30-inch rise?
A 30-inch rise is exactly at the single-run limit, so it needs one 30-foot run at the 1:12 maximum slope, plus a 60-inch landing at the bottom and a 60-inch landing at the top. That is 30 feet of ramp and 10 feet of landings, or about 40 feet of straight-line footprint. If the site cannot take 40 feet in a straight line, the usual answer is a switchback: turn the ramp at a landing, which must then be at least 60 inches by 60 inches, and run the second leg back alongside the first. A switchback roughly halves the length but doubles the width you need.
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Get a Free DemoRamp requirements vary with occupancy, site conditions and the code adopted in your jurisdiction, and state and local accessibility codes frequently exceed the federal ADA standard. All calculations are estimates based on the 2010 ADA Standards for Accessible Design and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a design prepared by a qualified designer or engineer, a plan review, or applicable local code requirements.