Wheelchair ramp calculator: how long does a wheelchair ramp need to be?
24 ft of ramp
1:12, 8.33% or 4.76° · 2 landings of 60 in, 34 ft in a straight line · handrails required · for a 24 in rise, ADA
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Enter it the way you measured it: 4.5, 4 1/2,
3/8 or 10' 6".
24 ft of ramp
1:12, 8.33% or 4.76° · 2 landings of 60 in, 34 ft in a straight line · handrails required
Source: 2010 ADA Standards for Accessible Design, 405 Ramps (U.S. Department of Justice), read October 24, 2026. Read the source
A 24 inch rise needs 24 ft of ramp at the ADA maximum slope of 1:12 (8.33%, 4.76°), in one run with a 60 inch landing at the top and bottom: 34 ft in a straight line, by the 2010 ADA Standards.
A worked example
A 41 inch rise to a public entrance needs 41 ft of ramp. 41 inches is over the 30 inch limit for one ADA run, so it takes 2 runs of 20.5 in of rise and 20.5 ft each, with 3 landings of 60 in: 56 ft if it runs straight. Each run rises more than 6 in, so it gets handrails 34 to 38 in high.
What is the ADA slope for a wheelchair ramp?
1:12 at the steepest: one inch of rise for every 12 inches of run, 8.33% or 4.76°, by section 405.2 of the 2010 ADA Standards. In an existing building short of room, Table 405.2 allows 1:10 for a rise of 6 in at most and 1:8 for 3 in at most; steeper than 1:8 is prohibited.
How often does a wheelchair ramp need a landing?
After every 30 inches of rise, by ADA 405.6, with a landing at the top and bottom of each run at least 60 in long, and 60 × 60 in where the ramp turns. At 1:12 that is a landing every 30 ft of ramp.
How steep can a ramp at a house be?
IRC 2021 R311.8.1 allows 1:12 for the ramp at the required exit door and 1:8 for any other ramp, with landings at least 36 in deep at the top and bottom. Steeper than 1:12, the ramp needs a handrail on at least one side, 34 to 38 in high.
What else it is called
Also called a handicap ramp, ADA ramp or accessibility ramp; the 1:12 rule is the ramp slope, one inch of rise for each foot of run. Searched as a wheelchair ramp slope calculator, ADA ramp calculator or wheelchair ramp length calculator.
Ramp length by rise
| Total rise | Ramp at 1:12 | ADA runs and landings | ADA straight length | Home ramp at 1:8 (IRC) |
|---|---|---|---|---|
| 6 in | 6 ft | 1 + 2 | 16 ft | 4 ft |
| 12 in | 12 ft | 1 + 2 | 22 ft | 8 ft |
| 18 in | 18 ft | 1 + 2 | 28 ft | 12 ft |
| 24 in | 24 ft | 1 + 2 | 34 ft | 16 ft |
| 30 in | 30 ft | 1 + 2 | 40 ft | 20 ft |
| 36 in | 36 ft | 2 + 3 | 51 ft | 24 ft |
| 48 in | 48 ft | 2 + 3 | 63 ft | 32 ft |
| 60 in | 60 ft | 2 + 3 | 75 ft | 40 ft |
One foot of ramp per inch of rise at 1:12, the ADA maximum and the IRC maximum at the required exit door; 1:8 is the IRC maximum for other home ramps. ADA runs rise 30 in at most, with a 60 in landing at the top and bottom of each run.
Where the numbers come from
- Slope, rise and landings: 2010 ADA Standards for Accessible Design, 405.2 «running slope not steeper than 1:12», 405.6 «The rise for any ramp run shall be 30 inches (760 mm) maximum», 405.7.3 landings «60 inches (1525 mm) long minimum», 405.7.4 60 × 60 in at a change in direction, 405.8 handrails on runs that rise more than 6 in, 505.4 handrails 34 to 38 in high. Read October 24, 2026. 2010 ADA Standards
- Ramps at a house: IRC 2021 R311.8, as printed in the 2021 Seattle Residential Code chapter 3 with no Washington amendment to it: 1:12 for a ramp serving the required egress door and 1:8 for other ramps (R311.8.1), a landing at least 36 in deep at the top and bottom (R311.8.2), a handrail on at least one side above 1:12 (R311.8.3). Read October 24, 2026. IRC 2021 chapter 3 (PDF)
- The rest is arithmetic: ramp ft = rise in × 12 ÷ 12 at 1:12 (× 8 ÷ 12 at 1:8); ADA runs = rise ÷ 30, rounded up, each with a landing at both ends; slope % = 100 ÷ 12, angle = atan(1 ÷ 12).
The ramp length is the run measured level along the slope. Landings are as wide as the ramp, and an ADA landing where the ramp turns is 60 × 60 in, so a ramp that switches back takes more room than the straight length suggests.
By Javier Miralles · Last updated . How this site is made.
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