ADA Ramp Calculator
Enter the Rise. Default 1:12 (or a gentler 1:16 / 1:20) gives the shortest run, the sloped length, how many runs a 30 in rise cap splits it into, and how many intermediate landings sit between them. Geometry from 2010 ADA Standards §405 — not a pass or fail.
This page's URL keeps these numbers, so someone else opening the link will see the same result.
Diagram
Not to scale| Slope | Run (in) | Ramp Length (in) |
|---|---|---|
| 1:12 | 288.00 | 289.00 |
| 1:16 | 384.00 | 384.75 |
| 1:20 | 480.00 | 480.60 |
What this ADA ramp calculator returns
The length this page returns first is the run — flat along the ground, not the sloped surface. At 1:12, run in inches is 12 × rise in inches. One run cannot rise more than 30 in, so 24 in is one run and no intermediate landing; 36 in splits into two runs with one landing between them.
| Rise | Run | Ramp length | Runs | Intermediate landings |
|---|---|---|---|---|
| 7 in | 84 in (7.0 ft) | 84.29 in (7.0 ft) | 1 | 0 |
| 12 in | 144 in (12.0 ft) | 144.50 in (12.0 ft) | 1 | 0 |
| 2 ft (24 in) | 288 in (24.0 ft) | 289.00 in (24.1 ft) | 1 | 0 |
| 36 in | 432 in (36.0 ft) | 433.50 in (36.1 ft) | 2 | 1 |
Top and bottom landings are each 60 in clear, and the walking surface is 36 in clear. Handrails are a separate check once rise is over 6 in. Those are §405 constants on the page, not a computed pass.
The current address keeps this rise and slope, so opening the link again shows the same numbers.
Two 7 in steps need 14 ft of run; four need 28 ft
ADA does not set stair height. This page treats one step as 7 in — the same 7 in row above. Two steps are a 14 in rise: 168 in (14.0 ft) of run at 1:12, still one run. Four steps are 28 in: 336 in (28.0 ft), still under the 30 in cap.
| What you have | Rise | Run at 1:12 | Runs | Intermediate landings |
|---|---|---|---|---|
| 2 steps (7 in each) | 14 in | 168 in (14.0 ft) | 1 | 0 |
| 4 steps (7 in each) | 28 in | 336 in (28.0 ft) | 1 | 0 |
| 4 ft rise | 48 in | 576 in (48.0 ft) | 2 | 1 |
A 4 ft rise is over 30 in, so it splits. Measure the actual rise if the stairs are not 7 in each; then type that number in the calculator.
1:16 is the same rise, more run — not a second formula
Pick 1:16 when you want a gentler slope, not because 1:12 ran out of room. For the default 24 in rise, 1:12 is 288 in of run; 1:16 is 384 in; 1:20 is 480 in. The extra length is the extra ratio. Runs and landings stay the same because the 30 in cap is on rise, not on slope.
| Slope | Run | Ramp length | Runs |
|---|---|---|---|
| 1:12 | 288 in (24.0 ft) | 289.00 in (24.1 ft) | 1 |
| 1:16 | 384 in (32.0 ft) | 384.75 in (32.1 ft) | 1 |
| 1:20 | 480 in (40.0 ft) | 480.60 in (40.0 ft) | 1 |
If the 1:12 run does not fit the site, the next move is a switchback — not a steeper ramp.
The 60 in landing adds ground, not slope
Run is only the sloped part. Each intermediate landing is a level 60 in clear. Add those after the run; do not fold them into the 1:12 multiply. For a 4 ft rise at 1:12, the sloped run is 576 in; one landing makes the path along the route 636 in. Top and bottom landings are another 60 in each at the ends — not in that path number.
| Rise | Sloped run | Intermediate landings | Path with those landings |
|---|---|---|---|
| 2 ft (24 in) | 288 in (24.0 ft) | 0 | 288 in (24.0 ft) |
| 36 in | 432 in (36.0 ft) | 1 | 492 in (41.0 ft) |
| 4 ft (48 in) | 576 in (48.0 ft) | 1 | 636 in (53.0 ft) |
If the run does not fit, do not steepen it
Short on space? Keep the 1:12 (or gentler) slope and fold the length with a switchback — a level landing and a turn — instead of making the ramp steeper. This page is not a compliance verdict, a permit, or engineering advice. Check the figures against 2010 ADA Standards §405.
For any-purpose slope and length — sheds, cars, trailers — use the ramp calculator.
Frequently asked questions
How long does an ADA ramp need to be for a given rise?+
At 1:12, the run along the ground is 12 times the rise. A 7 in rise needs 84 in of run; 12 in needs 144; 24 in (2 ft) needs 288; 36 in needs 432 and splits into 2 runs with 1 intermediate landing. Ramp length is the sloped surface, a little longer than the run. The table under the calculator works these four heights.
How long is an ADA ramp for two steps, four steps, or a 4 ft rise?+
ADA does not set stair height. This page treats one step as 7 in — the same 7 in row. Two steps are a 14 in rise and 168 in of run at 1:12; four steps are 28 in and 336 in. A 4 ft rise is 48 in: 576 in of run, 2 runs, 1 intermediate landing.
When should I use 1:16 instead of 1:12?+
When you want a gentler slope, not because 1:12 failed. Same 24 in rise: 1:12 is 288 in of run, 1:16 is 384 in, 1:20 is 480 in. The extra length is the extra ratio. The 30 in rise-per-run cap does not change, so 24 in is still one run.
What is the ADA maximum ramp length, and where do landings come from?+
There is not a separate 30-foot length rule. A single run cannot rise more than 30 in. At 1:12 that is a 30 ft run. If the total rise is over 30 in, split it into more than one run with a level landing between them. Top and bottom landings are also 60 in clear; this page counts the intermediate ones from the 30 in cap.
Does the 60 inch landing count toward the total length?+
The sloped run does not include it. Each intermediate landing is level and 60 in clear. For a 4 ft rise at 1:12, the sloped run is 576 in; add one landing and the path along the route is 636 in. Top and bottom landings are another 60 in each, counted at the ends, not in that path number.
Is this an ADA, wheelchair, handicap, or disabled ramp calculator?+
Same cluster, same geometry. People search those names for the 2010 ADA Standards §405 slope and length. This page uses the 1:12 cap (or a gentler 1:16 / 1:20) and the 30 in rise-per-run split. It is not a compliance, permit, or engineering opinion.