Thirty inches: the tallest single run
Thirty inches is the most one ramp run may climb. At 1:12 that makes 30 ft the longest run allowed without a level landing to rest on, and this rise is the last one that can be built as one run, with no landing part way up.
One more inch changes the layout: a 31 inch rise needs 2 runs and an intermediate landing, and its footprint goes from 35 ft to 41 ft. Measure the rise carefully at this height, from the ground at the foot of the ramp to the finished floor inside the door.
30 inch rise at each slope
| Slope | Ramp length (run) | Along the surface | Percent | Angle | Runs | Footprint with landings |
|---|---|---|---|---|---|---|
| 1:12 (ADA maximum) | 30 ft | 30.10 ft | 8.3% | 4.8° | 1 | 35 ft |
| 1:16 | 40 ft | 40.08 ft | 6.3% | 3.6° | 1 | 45 ft |
| 1:20 | 50 ft | 50.06 ft | 5.0% | 2.9° | 1 | 55 ft |
The footprint adds a 5 ft landing at the top. Allow 5 ft of clear, level space at the bottom too: with it the 1:12 ramp needs 40 ft from end to end. That bottom space is not in the concrete estimate below.
Is my ramp too steep for 30 inches?
Slope is rise ÷ run. For a 30 inch rise, a ramp shorter than 30 ft is steeper than 1:12:
| Ramp length | Slope | Percent | Angle | Within 1:12? |
|---|---|---|---|---|
| 26 ft | 1:10.4 | 9.6% | 5.5° | No, 4 ft too short |
| 28 ft | 1:11.2 | 8.9% | 5.1° | No, 2 ft too short |
| 30 ft | 1:12 | 8.3% | 4.8° | Yes |
| 34 ft | 1:13.6 | 7.4% | 4.2° | Yes |
Materials for the 30 ft ramp
A wood ramp 30 ft long and 36 inches wide takes 65 rows of 5/4×6 deck boards laid across it, 215 lineal feet with 10% extra, on 4 joists per run at 16 inch centers (133 lineal feet). The 4 inch concrete for the top landing is 0.34 cubic yards, about 16 bags of 80 lb mix. Built 48 inches wide, the decking rises to 286 lineal feet on the same 4 joists per run. Handrails on both sides, with a 12 inch level extension at the top and bottom of the run, come to 65 lineal feet of rail. Posts, brackets and footings are not in these figures.
Ramp length for nearby rises
| Rise | 1:12 | 1:16 | 1:20 | Runs | Footprint at 1:12 |
|---|---|---|---|---|---|
| 24 in | 24 ft | 32 ft | 40 ft | 1 | 29 ft |
| 28 in | 28 ft | 37.33 ft | 46.67 ft | 1 | 33 ft |
| 30 in | 30 ft | 40 ft | 50 ft | 1 | 35 ft |
| 36 in | 36 ft | 48 ft | 60 ft | 2 | 46 ft |
Coming down steps instead of a measured height? See a ramp for 4 steps or a ramp for 5 steps, or read the ramp length and slope guide.
Want to change anything else? The calculator above is the full Wheelchair Ramp Calculator: edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
How long does a wheelchair ramp need to be for a 30 inch rise?
30 ft at the 1:12 maximum slope, because every inch of rise needs 12 inches of ramp. With the landings it takes up 35 ft. At 1:16 the ramp is 40 ft and at 1:20 it is 50 ft.
What is the longest wheelchair ramp without a landing?
30 ft at 1:12, because one run may rise 30 inches at most. At 1:16 the same 30 inch run is 40 ft long, and at 1:20 it is 50 ft.
What is the slope of a 30 ft ramp with a 30 inch rise?
1:12, which is 8.3% or 4.8 degrees. Divide the rise by the run in the same unit: 30 ÷ 360 inches = 0.0833.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.