Ramp Calculator
Ramp length and landings for a rise at a given slope ratio.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Run = rise × slope ratio n (1:12 → run = 12 × rise)
Sloped length = √(rise² + run²)
Ramp runs = ⌈ rise ÷ max rise per run ⌉; intermediate landings = runs − 1
Handrail = sides × (sloped length + landing lengths)
Run the calculation to see each step with your own numbers.
24 in rise, 1:12 slope, handrails both sides, 30-in max rise per run.
Run = 2 ft × 12 = 24 ft
Sloped length = √(2² + 24²) = 24.08 ft
Runs = ⌈24 in ÷ 30 in⌉ = 1 → 0 intermediate landings; footprint ≈ 24 ft + top/bottom landings
Handrail = 2 × 24.08 = 48.2 ft
- Straight ramp. A switchback or dogleg adds a 60-in × 60-in turning landing at each turn — add those to the footprint.
- Slope ratio is the running slope. ADA/IBC: 1:12 maximum for new work, 1:16–1:20 preferred; cross slope ≤ 1:48; each run rises ≤ 30 in; landings ≥ 60 in long and at least as wide as the ramp.
- This sizes the ramp geometry — it does not check local code adoption, occupancy, edge protection, or loading. Confirm with your building department.
- Top and bottom landings are required but not added to the footprint figure — add 5 ft at each end.
- How long does a wheelchair ramp need to be?
- At the ADA maximum of 1:12, you need 1 foot of ramp run for every inch of rise — so a 24-inch porch needs 24 feet of ramp, plus level landings top and bottom. Gentler slopes (1:16–1:20) are longer but much easier to use, especially for someone self-propelling.
- What slope ratio should I use?
- 1:12 is the steepest allowed for new construction. 1:16 to 1:20 is much easier to self-propel and is worth the extra length wherever you have room for it.
- How much space does a switchback ramp need?
- Each turn adds a 60 in by 60 in turning landing. A tall rise done as a switchback fits in a much smaller footprint than a straight run, but you add a landing at every direction change.
Ramp geometry
Run = rise × slope ratio; sloped length = √(rise² + run²). Standard geometry.
Slope & landing limits
2010 ADA Standards §405 (running slope ≤ 1:12, rise ≤ 30 in per run, landings ≥ 60 in) and IBC §1012. Referenced for the limits shown; confirm the code edition your jurisdiction enforces.
About the Ramp Calculator
The Ramp Calculator turns a total rise and a slope ratio into the horizontal run, the sloped surface length to build, the number of intermediate landings, and the handrail length. It applies the common accessibility limits — a 1:12 maximum running slope for new work, and a level landing after every 30 in of rise — but it sizes geometry only and does not check which code edition your jurisdiction enforces. Top and bottom landings are required but not added to the footprint figure.
What you enter
- Total rise (ground to threshold)
- Slope ratio (1 : n) — The 'n' in 1:n. ADA maximum is 1:12 for new construction; 1:16 to 1:20 is easier to use.
- Handrails
- Max rise per ramp run before a landing — ADA: a single ramp run may rise at most 30 in before a level landing.
What you get back
- Horizontal run (total) — the exact result of the calculation.
- Sloped surface length (total) — The actual length of ramp surface to build (hypotenuse). Slightly longer than the run.
- Intermediate landings — Plus a level landing at the top and bottom (not counted here). Each landing ≥ 60 in long.
- Total footprint length (ramp + landings) — Run plus 5 ft per intermediate landing. Add top/bottom landings and any switchback turns.
- Handrail length — the exact result of the calculation.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
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Part of the Accessibility calculators.