Check a wheelchair or access ramp before you build or buy. Enter the rise and either a target slope, the horizontal run, or the ramp's surface length, and the calculator gives the slope as a 1:x ratio, a percent grade, and degrees, compares it with the ADA 2010 Standards (1:12 maximum, 30 inches of rise per run, 60 inch landings, handrails over 6 inches), and draws a side view against the 1:12 line.
Building steps instead of a ramp? The stair calculator works out risers and treads. For decks that need a ramp, size the framing with the deck calculator, and the percentage calculator handles any other grade math.
Frequently asked questions
What is the ADA maximum slope for a ramp?
Under the 2010 ADA Standards for Accessible Design, section 405.2, a ramp may be no steeper than 1:12 — one inch of rise for every 12 inches of horizontal run, which is 8.33% or about 4.8 degrees. Each run may climb at most 30 inches (section 405.6), so a single run at 1:12 is at most 30 feet long. Existing sites where space is limited may use 1:10 for a rise of 6 inches or less, or 1:8 for 3 inches or less (Table 405.2).
How long does a wheelchair ramp need to be?
Multiply the rise in inches by 12 for an ADA 1:12 ramp: a 24 inch rise needs 288 inches, or 24 feet, of horizontal run. Rises above 30 inches need more than one run, with a level landing at least 60 inches long between runs, so a 36 inch rise at 1:12 needs 36 feet of ramp plus a 5 ft landing. Many power-chair and scooter users prefer a gentler 1:16 or 1:20, which the length table shows side by side.
How do I convert a ramp slope to percent or degrees?
Percent grade is rise ÷ run × 100, so 1:12 is 1 ÷ 12 × 100 = 8.33%. Degrees is the arctangent of rise ÷ run: atan(1/12) = 4.76°. The ratio 1:x is run ÷ rise. Note that ramp length measured along the surface is slightly longer than the horizontal run (the hypotenuse), which matters when buying a portable ramp sold by its length — enter it in Ramp length mode and the calculator solves the run for you and checks it against ADA.
When does a ramp need handrails and landings?
ADA section 405.8 requires handrails on both sides when a ramp rises more than 6 inches. Section 405.7 requires a level landing at the top and bottom of every run, at least 60 inches long and as wide as the ramp; where the ramp changes direction, the landing must be at least 60 × 60 inches. The clear width between handrails is 36 inches minimum, and cross slope may not exceed 1:48. A slope of 1:20 or flatter is a walk, not a ramp, so these rules do not apply to it. Curb ramps follow separate rules in section 406.
Does the ADA apply to a ramp at my house?
The ADA covers public accommodations, commercial facilities, and government buildings, not private single-family homes. It is still the standard most people design home ramps to, because 1:12 is manageable for many manual wheelchair users. Local residential codes may allow different slopes, and portable-ramp makers list steeper ratios for loading equipment rather than people. Check your wheelchair or scooter manual for its rated maximum incline, and your local building department for permits. The part of a home used as a business open to clients can be covered, so check before assuming a ramp is exempt.