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Wheelchair Ramp Length Calculator

Enter the height you need to climb and this calculator returns the ramp length to order. It sizes to the ADA 1:12 slope, meaning 12 inches of ramp for every 1 inch of rise, and also shows the shorter assisted and unoccupied lengths. Measure your rise first: the vertical distance from the lower ground up to the top of your threshold, step, or porch.

Diagram showing where to measure rise height for ramp selection

Measure from the ground to the top of the highest step or landing.

Or enter exact rise: in.
Enter your rise above to see the recommended ramp length.

A 1:12 slope means 12 inches of ramp for every inch of rise. The bigger the second number, the gentler the climb. Gentler is always safer, so verify local building code before installing.

Why slope matters
SlopeInclineSafe use
1:12≈4.8°Independent wheelchair use. The ADA standard.
1:6≈9.5°Steepest acceptable for an occupied chair or scooter, and only with a qualified helper.
1:4≈14°Unoccupied transport only, with no one riding.

Read the ratio as rise to length: 1:4 means every inch of rise needs 4 inches of ramp, so it climbs three times faster than 1:12. Some manufacturers write these same two slopes as 2:12 and 3:12, which are identical inclines in unreduced form.

Use the longest ramp your space allows and follow your equipment’s owner manual. A rise over 30 inches needs a landing or platform.

How to measure your rise

  1. Rest a level or straight board on the top surface (the threshold, step, or porch edge) so it extends out over the lower ground.
  2. Measure straight down from the underside of that board to the ground. That vertical distance is your rise. Use it, not the diagonal.
  3. Enter the rise above. If it lands between two inches, round up.

For a fuller walkthrough covering door swing, sloping ground, and where people most often measure wrong, see the complete guide to ramp length and slope.

What your result means

The 1:12 slope is the ADA maximum for accessible ramps and the right target for independent use whenever you have the room. Always follow your ramp and mobility device manufacturer's instructions.

The two shorter figures are steeper, and each has one narrow use: 1:6 is the steepest acceptable for an occupied chair or scooter and only with a qualified helper, and 1:4 is for moving an unoccupied chair or scooter with no one riding. (Some manufacturers write these as 2:12 and 3:12, the same slopes in unreduced form.) Gentler is always safer, so choose the longest ramp your space allows and follow your equipment's owner manual.

If your rise is more than 30 inches, it needs to be built as multiple runs with a level landing between them rather than one continuous ramp. Request a quote and we'll size the system.

Which ramp fits your rise

Length is one half of the answer; the rise decides the type as well. A door sill or single low threshold calls for a threshold ramp. One or two steps usually means a multifold portable ramp that folds for storage and travel. A raised porch, or any rise past a couple of feet, is modular ramp system territory, built in sections and able to carry the landings a taller rise requires.

Browse everything in the wheelchair ramps collection, and check each product's rated rise and weight capacity against your measurements before ordering.

General advice notice. This calculator provides general educational information, not a site assessment, engineering opinion, or legal determination of ADA compliance. Requirements vary with your site and with state and local building codes, which are sometimes stricter than the federal ADA Standards. Verify any regulatory requirement against current ADA / U.S. Access Board sources and your local code before purchasing or installing.