JB PARCELADA Ramp Calculator
Enter the height you need to climb and get the ramp the ADA Standards require: horizontal length, how many runs, how many landings, whether it needs handrails, and how much ground the whole thing covers.
How this calculator works
Ramp length is rise times slope. The 2010 ADA Standards cap new ramps at 1:12, one inch of rise for every twelve inches of run, which is about 8.33 percent or 4.8 degrees. So every inch you need to climb costs a foot of ramp. A 24 inch rise needs 24 feet of ramp before you add a single landing.
No single run may rise more than 30 inches. Past that the ramp has to break into runs with a level landing between each one, at least 60 inches long and as wide as the ramp. There also has to be a landing at the top and at the bottom, and any landing where the ramp changes direction needs to be at least 60 by 60 inches so a wheelchair can turn.
A run that rises more than 6 inches needs handrails on both sides, 34 to 38 inches high, extending at least 12 inches beyond the top and bottom of the run. Clear width between the handrails has to be at least 36 inches. Those two rules together are why a code-compliant ramp is wider and longer than people expect.
The number that usually matters to an owner is the footprint. A 36 inch porch rise at 1:12 needs 36 feet of ramp in two runs plus three landings, 51 feet end to end if laid out straight. Whether that fits between the entrance and the property line, or inside a setback, decides whether you build a ramp, add a switchback, or lower the entry instead.
Worked example: a 24 inch entrance on a small commercial building
24 inches from the parking lot to the door threshold, new work at 1:12, 36 inch clear width.
| Ramp length, horizontal | 24 ft 0 in |
|---|---|
| Ramp runs | 1 |
| Landings between runs | 0 |
| Total length with landings | 34 ft 0 in |
| Sloped surface length | 24 ft 1 in |
| Handrails | Required on both sides |
One run, because 24 inches is under the 30 inch limit. Now raise the rise to 36 inches: the ramp grows to 36 feet, splits into two runs with one landing between them, and the straight-line footprint reaches 51 feet. At a gentler 1:16 the same 36 inches needs 48 feet of ramp and 63 feet overall. That is why a tall entrance often ends up with a switchback, or with the entry lowered instead.
Where the numbers come from
Dimensions are from the 2010 ADA Standards for Accessible Design: section 405 for ramps, Table 405.2 for existing sites, and section 505 for handrails. The residential slope is from the International Residential Code, section R311.8. State and local codes can add to these, and the building official has the final word.
Questions investors ask
What is the ADA ramp slope?
The steepest running slope allowed for a new ramp is 1:12, one inch of rise per twelve inches of run, about 8.33 percent. Gentler is always allowed and easier to use. Cross slope may not exceed 1:48. A path at 1:20 or flatter is treated as a walking surface rather than a ramp.
How long does a ramp need to be for a 24 inch rise?
24 feet of ramp at 1:12, in a single run because 24 inches is under the 30 inch limit per run. Add a 60 inch landing at the top and at the bottom and the straight-line footprint is 34 feet. At 1:16 the ramp itself is 32 feet.
When does a ramp need handrails?
When a run rises more than 6 inches. Handrails then go on both sides, with the top of the gripping surface 34 to 38 inches above the ramp, and they extend at least 12 inches horizontally past the top and bottom of each run.
How often does a ramp need a landing?
Every 30 inches of rise, plus one at the top and one at the bottom. Each landing is at least 60 inches long and at least as wide as the ramp run leading to it. A landing where the ramp changes direction must be at least 60 by 60 inches.
Can a ramp be steeper on an existing building?
Only a little, and only where space rules out 1:12. The ADA Standards allow up to 1:10 for a total rise of 6 inches or less, and up to 1:8 for a rise of 3 inches or less, on existing sites, buildings, and facilities. Anything taller has to meet 1:12.
Does a house or a small rental need an ADA ramp?
A private single-family home is generally not covered by the ADA, though a ramp built there still has to meet the residential code, which caps ramps at 1:12 with 1:8 allowed where site constraints make 1:12 infeasible. New multifamily buildings with four or more units fall under the Fair Housing Act design requirements, and commercial space falls under the ADA. If you are buying a building to lease as retail or office, price the entrance before you price the rent.
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Screening a real property? Pull its appraised value, assessed value, acreage, land use, and last recorded sale off the JB PARCEL parcel map and drop the real numbers into this calculator instead of guessing. Coverage runs across every county we carry.