Carpentry Calculators

Wheelchair ramp calculator

Enter the rise from the ground to the door. This works out how long the ramp runs at 1:12 or gentler, where the landings go, and checks it against the 2010 ADA Standards.

in

Ground to the top of the threshold

12 for 1:12, 16 for 1:16, 20 for 1:20

in

Between the handrails

in

Each landing, in the direction of travel

Total length, landings included

47 ft

Sloped run

32 ft

Runs

2

Landings between

1

Slope

4.76°

  • Running slope no steeper than 1:12 — passes1:12 is 4.76°, at or under the 4.76° of 1:12.
  • At least 36" clear between handrails — passes42" clear.
  • Landings at least 60" long — passes60" at the top, the bottom and between runs.

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Landings in black, runs in amber — height exaggerated to show the slope

The layout, bottom to top

Bottom landing
60"
2 runs, eachRises 16" over 192" level — 192 11/16" along the surface
16 ft
1 landing between runsNo run may climb more than 30", so the rise is split evenly
60"
Top landing
60"
Straight-line totalA switchback folds the same runs back on themselves; its turning landings need 60" x 60"
47 ft

The same rise at gentler slopes

  • 1:124.76° · 2 runs32 ft sloped · 47 ft total
  • 1:163.58° · 2 runs42 ft 8 in sloped · 57 ft 8 in total
  • 1:202.86° · 2 runs53 ft 4 in sloped · 68 ft 4 in total

1:12 is the steepest the ADA Standards allow, not a target. A gentler ramp is easier to push a chair up and to walk down in the wet, at the cost of length. At 1:20 or gentler the Standards call it a walking surface rather than a ramp.

Handrails on both sides

A run that rises more than 6" needs a handrail on each side (ADA 405.8), continuous along the run, 34" to 38" above the surface, and extending 12" level past the top and bottom of each run. Edges need protection so a wheel or a cane cannot slip off (405.9).

Which rules apply to your ramp

These checks are the 2010 ADA Standards (section 405), which bind public and commercial buildings. A ramp at a private house is often governed only by the local residential code — sometimes with different limits, sometimes by none — and a ramp paid for by a grant or insurer may have its own. Treat these as defaults, not law, and ring the building department before you build.

About access ramps

How long does a wheelchair ramp need to be?
One foot of ramp for every inch of rise at the ADA maximum of 1:12, before landings. A 24" rise needs 24 ft of sloped run, and with a 60" landing at the top and the bottom the whole thing is 34 ft long in a straight line. A gentler slope is easier to use and longer again.
What is a 1:12 slope in degrees?
4.76°, or a grade of 8.33% — one inch of rise for every twelve inches of run. That is the steepest running slope the 2010 ADA Standards allow for a new ramp (section 405.2). 1:16 is 3.58° and 1:20 is 2.86°; at 1:20 or gentler the Standards stop calling it a ramp at all.
When does a ramp need a landing in the middle?
Whenever the total rise is more than 30": no single run may climb more than that (405.6), and every run needs a landing at least 60" long at its top and bottom (405.7). A 36" rise therefore breaks into 2 runs of 18" each with 1 landing between them. Where the ramp turns, the landing has to be 60" x 60".
When does a ramp need handrails?
When a run rises more than 6" — then it needs a handrail on both sides (405.8), 34" to 38" above the ramp surface and running 12" level past the top and bottom. The clear width of at least 36" is measured between the handrails, so the framing has to be wider than that.
Does a ramp at my house have to meet the ADA?
Often not. The ADA Standards govern public accommodations and commercial facilities; a ramp at a private house is usually covered by the local residential code, which may set different limits or none. The ADA figures are still the sensible ones to build to — they are what a wheelchair user can manage unassisted — but the building department decides what is required where you are, and a grant or insurer paying for the ramp may have its own rules. Ring them before you build.

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