Free wheelchair ramp calculator. Enter the rise height for ADA 1:12 compliant ramp length, slope angle, grade, landings, and handrail rules.
Your results will appear here.
Enter your values and press Calculate.
Enter the vertical rise in inches and pick a slope ratio. The run (horizontal distance) is rise times the ratio number: at 1:12, a 24-inch rise needs 288 inches of run. The ramp surface length comes from the Pythagorean theorem, the angle from arctan(1/n), and the grade is 100/n percent. ADA caps each ramp run at 30 inches of rise, so taller rises split into sections with level landings between them.
A 1:12 slope means 1 inch of rise for every 12 inches of run. Multiply your rise by 12 to get the horizontal distance: 24 inches of rise needs 288 inches (24 feet) of run.
The actual ramp board is slightly longer than the run because it sits at an angle: length = sqrt(rise² + run²⁾. For that 24-inch rise the board is about 289 inches. The slope angle is arctan(1/12) = 4.76 degrees, and the grade is 100/12 = 8.33%. Gentler ratios like 1:16 and 1:20 make climbing easier but need much more space.
Measure the total vertical rise from the ground to the top surface (door threshold, porch floor, or step top) in inches. Pick your slope ratio: 1:12 is the ADA standard, 1:16 and 1:20 are gentler, 1:10 and 1:8 are ADA exceptions for constrained existing sites.
The calculator returns the horizontal run, the true ramp surface length in inches and feet, the slope angle and grade, how many sections the ramp needs, and whether handrails are required.
The ADA Standards (2010, Section 405) set the widely used baseline: maximum slope 1:12, minimum clear width 36 inches, maximum 30 inches of rise per ramp run, and 60 × 60 inch level landings wherever a run ends or turns. Handrails are required on both sides when the rise exceeds 6 inches, and edge protection keeps wheels from slipping off.
Residential ramps are not always legally bound by ADA, but the 1:12 rule is the safest design target for any wheelchair user, especially seniors.
Older guides still say handicap ramp instead of wheelchair ramp, but the rules are identical. As a quick slope ratio chart: 1:12 = 8.33%, 1:16 = 6.25%, 1:20 = 5%, 1:10 = 10%, 1:8 = 12.5%.
Where space constraints make 1:12 impossible on existing sites, ADA permits steeper slopes with strings attached: up to 1:10 for a maximum 6-inch rise, and up to 1:8 for a maximum 3-inch rise. These are exceptions, not a general license for steep ramps.
Steeper ramps demand more upper-body strength and are risky in wet or icy weather. If anyone using the ramp has limited strength, stick with 1:12 even when an exception would be legal.
Two standard steps total about 24 inches of rise. At ADA 1:12: run = 24 × 12 = 288 inches (24 feet). Ramp length = sqrt(24² + 288²⁾ = 289 inches (24.08 feet). Angle = 4.76 degrees, grade = 8.33%. One section (under the 30-inch cap), one landing at the top, and handrails required since the rise exceeds 6 inches.
Three steps (about 36 inches) at 1:12 need 432 inches of run and split into 2 sections with a middle landing.
Every ramp run needs a level landing at top and bottom, at least 60 × 60 inches so a wheelchair can rest and turn. Any run that changes direction needs a landing at the turn too. Landings must be as wide as the ramp.
Handrails go on both sides when the rise is over 6 inches, at 34 to 38 inches high, continuous along the full run, with edge protection (a curb or rail) so wheels cannot slip off the side.
Aluminum modular ramps are the common permanent choice: rust-proof, low maintenance, and resalable. Wood ramps cost less up front but need regular sealing and can get slippery. Concrete is the most durable and the most expensive to build. Portable folding ramps suit short rises and travel; suitcase-style ramps typically handle rises under about 6 inches.
Costs vary widely by region and rise height, so get local quotes for your exact measurements rather than trusting a national average.
1:12 maximum: 1 inch of rise for every 12 inches of horizontal run. That equals an 8.33% grade and a 4.76-degree angle.
Multiply the rise by the slope ratio number for the run (rise × 12 at 1:12), then apply the Pythagorean theorem: length = sqrt(rise squared + run squared). A 24-inch rise at 1:12 gives a 289-inch ramp.
A gentle slope rising 1 unit for every 12 units of horizontal distance. As a grade it is 8.33%, as an angle it is 4.76 degrees. It is the ADA maximum steepness for wheelchair ramps.
1:12 under ADA for new construction. On constrained existing sites, exceptions allow 1:10 (max 6-inch rise) and 1:8 (max 3-inch rise). Anything steeper is unsafe for most wheelchair users.
36 inches of clear width under ADA, measured between handrails. Wider is more comfortable, especially for turns.
Three standard steps are about 21 to 24 inches of rise. At 1:12 that needs 252 to 288 inches of run (21 to 24 feet), plus landings. Measure your actual rise rather than guessing from step count.
Landings: at the top and bottom of every run and wherever the ramp turns, minimum 60 × 60 inches. Handrails: on both sides whenever the rise exceeds 6 inches.
4.76 degrees, from arctan(1/12). The grade is 8.33%.
1:12 is the standard safe target. 1:16 or 1:20 is even easier to climb and better for seniors or manual wheelchair users with limited strength, if you have the space.
Under ADA, yes on both sides when the rise is more than 6 inches. Even where not legally required, handrails add real safety for every user.
Anything steeper than 1:8 is generally too steep and unsafe, and steeper than 1:12 fails ADA for new construction. Wet, icy, or long ramps should stay at 1:12 or gentler.
Shorter in length means steeper, which means harder and less safe. Only the narrow ADA exceptions (1:10 up to 6 inches of rise, 1:8 up to 3 inches) allow it, and only on constrained existing sites.
Estimate concrete volume and bags needed for slabs, footings and columns.
Count fence posts, rails, pickets and concrete bags - with depth and spacing guidance.
Find the exact number of steps, riser height, run and angle for any staircase.
Count the exact boards, rows, and linear feet your deck needs.