Sixteen inches: measure the room before choosing a slope
A 16 inch rise takes 16 ft of ramp at 1:12, 21.33 ft at 1:16 and 26.67 ft at 1:20. Counting the top landing and the 5 ft clear at the bottom, those need 26 ft, 31.33 ft and 36.67 ft in a straight line.
So measure first, from the door out to the nearest fence, driveway or sidewalk, and pick the gentlest slope that fits. If none fits in a straight line, a landing lets the ramp turn: it adds 5 ft of platform, but the two legs can then run along the house.
16 inch rise at each slope
| Slope | Ramp length (run) | Along the surface | Percent | Angle | Runs | Footprint with landings |
|---|---|---|---|---|---|---|
| 1:12 (ADA maximum) | 16 ft | 16.06 ft | 8.3% | 4.8° | 1 | 21 ft |
| 1:16 | 21.33 ft | 21.37 ft | 6.3% | 3.6° | 1 | 26.33 ft |
| 1:20 | 26.67 ft | 26.70 ft | 5.0% | 2.9° | 1 | 31.67 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 26 ft from end to end. That bottom space is not in the concrete estimate below.
Is my ramp too steep for 16 inches?
Slope is rise ÷ run. For a 16 inch rise, a ramp shorter than 16 ft is steeper than 1:12:
| Ramp length | Slope | Percent | Angle | Within 1:12? |
|---|---|---|---|---|
| 12 ft | 1:9 | 11.1% | 6.3° | No, 4 ft too short |
| 14 ft | 1:10.5 | 9.5% | 5.4° | No, 2 ft too short |
| 16 ft | 1:12 | 8.3% | 4.8° | Yes |
| 20 ft | 1:15 | 6.7% | 3.8° | Yes |
Materials for the 16 ft ramp
A wood ramp 16 ft long and 36 inches wide takes 35 rows of 5/4×6 deck boards laid across it, 116 lineal feet with 10% extra, on 4 joists per run at 16 inch centers (71 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 154 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 37 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 |
|---|---|---|---|---|---|
| 12 in | 12 ft | 16 ft | 20 ft | 1 | 17 ft |
| 14 in | 14 ft | 18.67 ft | 23.33 ft | 1 | 19 ft |
| 16 in | 16 ft | 21.33 ft | 26.67 ft | 1 | 21 ft |
| 18 in | 18 ft | 24 ft | 30 ft | 1 | 23 ft |
| 20 in | 20 ft | 26.67 ft | 33.33 ft | 1 | 25 ft |
Coming down steps instead of a measured height? See a ramp for 2 steps or a ramp for 3 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 16 inch rise?
16 ft at the 1:12 maximum slope, because every inch of rise needs 12 inches of ramp. With the landings it takes up 21 ft. At 1:16 the ramp is 21.33 ft and at 1:20 it is 26.67 ft.
How much space does a ramp for a 16 inch rise take?
At 1:12, 16 ft of ramp, 21 ft with the 5 ft landing at the door and 26 ft with 5 ft of clear space at the bottom. The clear width is at least 36 inches and the landings are at least 60 inches long.
What is the slope of a 16 ft ramp with a 16 inch rise?
1:12, which is 8.3% or 4.8 degrees. Divide the rise by the run in the same unit: 16 ÷ 192 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.