Wheelchair Ramp Calculatorby AccessProof

Ramp fit planner

Will a ramp fit? Check the run before you build

Enter the rise and the straight distance you have. You will see the run ADA 1:12 needs, whether it fits, and what a switchback would take if it does not.

Runs locally in your browser. No signup, no upload.

Your measurements

Rise

Measure floor to floor, or the height of the step at the entrance.

Rise unit
Available straight run

The level distance from the top landing to the point where the ramp can end.

Run unit
Space to turn or switch back?

A switchback turns the ramp back on itself, like a U. It needs width as well as length.

Narrowest clear width along the route, in feet. Leave blank if you do not know.

Planning aid, not a certification. Check the final design with your local building department.

Your fit check

At 1:12, 24 in of rise needs 24 ft. You have 20 ft, so it does not fit: 4 ft more is needed. A switchback could use 2 runs of 12 ft each.

Doesn't fit

Needs 4 ft more. You have 20 ft; this layout needs 24 ft.

Required run at 1:12
24 ft (7.32 m)24 in rise × 12 at 1:12. The slope alone, before landings.
Straight run you have
20 ft (6.1 m)The straight distance you entered.
Straight check length
24 ft (7.32 m)One run, so no intermediate landing. Top and bottom landings can be the existing porch and path.
Full footprint
34 ft (10.36 m)Run plus 2 landings at 5 ft each, if every landing has to sit inside the same space.
Gentler 1:16 option
32 ft (9.75 m)32 ft at 1:16 (6.25%). Needs 12 ft more.
Available width
Not enteredOptional. 36 in is the minimum clear width in ADA §405.5.

Switchback layout

If you can turn, 2 runs of 12 ft each, 3 landings, about 17 ft × 7 ft.

  • Runs: Each run rises 12 in. The ADA cap is 30 in per run.
  • Landings: 3 landings: top, bottom and 1 turn. At least 5 ft × 5 ft at each turn.
  • Footprint: About 17 ft along the runs × 7 ft across. Assumes 3 ft clear per run, 1 ft between parallel runs and a 5 ft turn landing at one end.

Estimate only, not a certified layout. A designer or contractor sets the final geometry, handrails and drainage.

Straight profile of the required 1:12 run. Schematic, not to scale. A switchback would fold this run into parallel legs.

What this planner does not do

  • No site survey. The answer uses the numbers you enter. Ground slope across the route, obstacles, door swing, setback lines and soil are not checked.
  • No grading or drainage. A ramp changes how water moves. The ground under and around it needs a fall away from the house, and that is a job for a contractor or engineer.
  • Not a substitute for a contractor or inspector. Permits, local amendments and the final layout still need a professional and your building department.

How the fit verdict works

  • The required run is the rise multiplied by 12, the ADA §405.2 maximum slope of 1:12.
  • The straight check adds a 60 in landing between runs when the rise is over 30 in (§405.6 and §405.7). The top and bottom landings can be the existing porch and path.
  • Fits comfortably means at least 2 ft (0.61 m) is left over. That margin is our planning rule, not a code requirement. Tightmeans the slope fits with less than 2 ft to spare. Doesn't fitmeans the straight route is short, and the planner shows how much is missing.
  • A switchback estimate gives each leg 3 ft of clear width, 1 ft between parallel runs and 5 ft turn landings at the ends (one end when there are two runs). Confirm the width before you rely on it.

Next steps. Get the full numbers, including handrails, landings and a cost estimate, then check the code text.

Planning aid, not a certification. The ADA applies to public accommodations and commercial facilities. A private single-family home ramp is not covered by the ADA (check your local residential code).