Wheelchair Ramp Calculator
This wheelchair ramp calculator turns a vertical rise into a compliant ramp. Enter the height the ramp has to climb — from the ground or grade up to the landing you are reaching — and it reads back the running slope three ways (as a 1:X ratio, a percentage and an angle), the ramp surface length, how many landings you need and where, and the straight-through footprint the ramp and its landings occupy.
It also checks the design against a standard, rule by rule. Pick ADA / IBC public, IRC residential, an ADA existing-site allowance or an occupant-use guidance ratio, and each limit that standard defines — running slope, rise per run, run per run, minimum width, and the existing-site total-rise cap — is listed with your actual value and a pass or fail. A multi-standard comparison shows the required length at 1:12, 1:10, 1:8 and the 2:12 guidance ratio side by side so you can see the trade-off, not just one answer.
Everything runs in your browser: no sign-up and nothing uploaded. Switch between metric and imperial at any time, export a CSV or print a set-out sheet. Building limits vary by jurisdiction and are amended locally, so treat every result as a starting estimate and confirm the final design with your local building authority (AHJ).
How to use the ramp calculator
Start in Length mode: enter the total rise and choose a standard, and the calculator builds the shortest compliant ramp at that standard's maximum slope — segmenting a tall rise into runs separated by landings and reading back the surface length, footprint and a full compliance report live as you type.
Switch to Check mode to test a ramp you have already measured: enter the rise and the horizontal run, and it reports the actual slope and flags any rule the pair breaks — a run that is too short for its rise legitimately fails. Use Fit mode when the space is fixed: enter the rise and the run you have available, and it finds the gentlest standard that still fits, or tells you the ramp will not fit straight so you can fold it back with a switchback.
How to size a wheelchair ramp in 5 steps
- Choose unitsPick metric or imperial at the top of the page. Every input and result converts as you switch between them.
- Pick an input modeChoose Length to size a ramp from the rise, Check to test a ramp you have already measured, or Fit to see whether a ramp fits the run you have available.
- Enter the riseType the total rise — the full height from the ground or grade up to the landing the ramp reaches. Add the run or available run in Check and Fit modes.
- Choose a standardSelect ADA / IBC public, IRC residential, an ADA existing-site allowance, occupant-use guidance, or enter custom limits for another jurisdiction.
- Read the resultsRead the slope, surface length, landings and footprint, then check the per-rule compliance report and the multi-standard comparison. Print or export the layout.
The parts of a ramp
A ramp run is the sloped surface itself. Its rise is the vertical height it climbs and its run is the horizontal distance it covers; the ratio of the two is the slope. The ramp surface length is the diagonal you actually walk — the square root of rise squared plus run squared — and is always a little longer than the horizontal run.
A landing is the level resting platform at the top and bottom of every ramp run, and between runs where a long ramp is broken into segments. Under ADA a landing is at least 60 in (1525 mm) long and at least as wide as the ramp. Where a ramp changes direction the landing must be a full 60 × 60 in (1525 × 1525 mm). The cross slope is the gentle side-to-side tilt across the ramp that sheds water; it is capped separately from the running slope.
Slope standards: ADA, IRC and existing sites
For a new public or commercial ramp the ADA 2010 Standards and the IBC cap the running slope at 1:12 — that is 8.33%, or one unit of rise for every twelve of run. A single ramp run may rise no more than 30 in (760 mm) and project no more than 30 ft (9 m) horizontally before a landing is required; at 1:12 those two caps coincide exactly, because 30 in × 12 = 30 ft. The ramp must be at least 36 in (915 mm) wide and its cross slope no steeper than 1:48 (about 2.08%).
The IRC residential standard also caps the slope at 1:12 for a ramp serving a required exit; its own text does not restate a clear width or cross slope, so this tool carries the ADA figures forward as a baseline and flags them as such. ADA's existing-site and alteration exceptions allow a steeper ramp only where space is genuinely constrained: 1:10 when the total rise is no more than 6 in (150 mm), and 1:8 when the total rise is no more than 3 in (75 mm). New construction may not use these steeper ratios. Occupant-use guidance figures such as 2:12 or 3:12 come from equipment vendors, not a building code, and this tool badges them accordingly.
Landings and total length
Because a single ADA ramp run may rise at most 30 in (760 mm), a taller rise is split into equal runs with a level landing between each. Divide the total rise by the 30 in cap and round up to get the number of runs; the calculator gives each run the same rise so every segment is independently compliant, then places a landing at the top, at the bottom, and between each pair of runs.
The landings add up quickly. A straight ADA ramp for a 30 in rise needs about 30 ft of ramp plus two 5 ft landings — roughly 40 ft of footprint in a straight line. Doubling the rise more than doubles the footprint, because each extra run brings its own landing. The segment table below the result lists every run and landing in order so you can set the ramp out from a single datum, and the footprint figure is what you check against the space you actually have.
Fitting a ramp into a tight space
A compliant ramp is long, and a straight run often will not fit the yard, stoop or landing you have. Fit mode takes the rise and the run available and searches the standards from gentlest to steepest — 1:12, then the 1:10 and 1:8 existing-site allowances where the rise is small enough to qualify — and reports the least-steep option whose full footprint fits. If nothing fits, it says so.
When a straight ramp will not fit, the usual answer is a switchback or L-shaped ramp that folds the run back on itself around a turn landing, so the same developed length occupies a compact footprint. The direction-change landing must be a full 60 × 60 in. This calculator reports the straight-through footprint and flags the switchback option; laying out the exact turn geometry is a follow-up step once you know the length you need.
Frequently asked questions
What slope should a wheelchair ramp be?
For a new public or commercial ramp the ADA and IBC cap the running slope at 1:12 — that is 8.33%, or one unit of rise for every twelve units of run. Gentler is always better. Steeper ratios of 1:10 or 1:8 are allowed only under ADA's existing-site exceptions, and only for small rises of 6 in and 3 in respectively.
How long does a wheelchair ramp need to be?
At the ADA 1:12 maximum, the ramp run is twelve times the rise: a 30 in (760 mm) rise needs 30 ft (9 m) of ramp run. On top of that you need a level landing at the top and bottom — at least 60 in (1525 mm) each — so the straight footprint for a 30 in rise is about 40 ft. This calculator gives the exact surface length and footprint for your rise.
What is the difference between an ADA ramp and an IRC residential ramp?
Both cap the running slope of an accessible or required-exit ramp at 1:12. The ADA 2010 Standards apply to public and commercial buildings and spell out width, landing, cross-slope and handrail rules in full. The IRC covers one- and two-family homes; its ramp section sets the 1:12 slope but does not restate a clear width or cross slope, so this tool carries the ADA figures forward as a baseline and flags them as such.
When does a ramp need a landing?
A level landing is required at the top and bottom of every ramp run, and between runs whenever the ramp is broken into segments. A single ADA ramp run may rise no more than 30 in (760 mm) or project more than 30 ft (9 m) horizontally, so any rise above 30 in needs at least one intermediate landing. Each landing must be at least 60 in (1525 mm) long and as wide as the ramp.
What are the 1:10 and 1:8 existing-site exceptions?
Where an existing site or alteration cannot accommodate a 1:12 ramp because of space limits, ADA Table 405.2 allows a steeper ramp for a small rise only: 1:10 when the total rise is no more than 6 in (150 mm), and 1:8 when the total rise is no more than 3 in (75 mm). New construction may not use these ratios — 1:12 is binding. This tool flags a rise that exceeds the exception's cap as a failure.
Do I need handrails on the ramp?
Under ADA, handrails are required on both sides of any ramp run that rises more than 6 in (150 mm) or runs more than 72 in (1830 mm) horizontally. Edge protection — a curb, rail or barrier — is also required along the sides of ramp runs and landings. The calculator flags when handrails are triggered, but treats them as hardware notes rather than a geometry pass or fail.
What is cross slope and why does it matter?
Cross slope is the gentle side-to-side tilt across the width of the ramp, separate from the running slope you climb. A little cross slope sheds water, but too much makes a chair pull to one side. ADA caps it at 1:48 (about 2.08%). This calculator only checks cross slope when you enter a value, so it never silently asserts a compliance you have not measured.
Does the calculator work in metric and imperial?
Both. Switch units at the top of the page and every dimension converts — rise, run, width, surface length and footprint. The engine works in SI internally and only converts for display, so switching units never changes the underlying layout or the compliance result.
Is the wheelchair ramp calculator private?
Yes. Every calculation runs entirely in your browser. Nothing you enter is sent to a server, and your inputs are saved only in your own browser's local storage.