Ramp Calculator
Thirty inches of rise at 1:12 is a 30.00 foot run, a 30.10 foot ramp, and 2 landings.
Last updated . Rise starts at thirty inches. The ratio starts at 12.
A ramp calculator for the horizontal distance, the sloping length, and the angle. The opening ratio is the steepest new ramp in the 2010 ADA Standards. Type a larger second number when the walk should be easier.
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Ramp run, length, and landings
The box opens at 12, the 2010 ADA 405.2 maximum for new work (1:12). A larger number is a gentler slope and still complies. A smaller number is steeper than that maximum. Landings follow 405.6 and 405.7 and do not use the ratio.
Results
Run, hypotenuse, and the 30 inch rise limit
The horizontal run is the rise multiplied by the second number in the ratio. At 30 inches, which is 2.50 feet, a ratio of 12 gives 30.00 feet of run. Ramp length is the full square root of run squared plus rise squared: the square root of 906.25 is 30.10 feet, or 9.18 meters. The angle is the arctangent of 1/12, 4.76 degrees, which is 8.33 percent.
Section 405.2 of the 2010 ADA Standards says ramp runs shall have a running slope not steeper than 1:12. That is a maximum, not a slope the standard tells you to build. Table 405.2 is only for existing sites: a slope steeper than 1:12 but not steeper than 1:10 may rise 6 inches, and a slope steeper than 1:10 but not steeper than 1:8 may rise 3 inches. Steeper than 1:8 is not allowed. Section 405.6 limits any one run to 30 inches of rise. Section 405.7 requires a landing at the top and the bottom of each run, so the landing count is the run count plus one. A 30 inch rise is one run and two landings. A 36 inch rise is two runs and three landings. The text is in the 2010 ADA Standards PDF, with the same sections at CORADA 405.2 and the Access Board’s ramp guide.
Worked rises
| Rise | Ratio | Run | Length | Angle | Landings |
|---|---|---|---|---|---|
| 30 in | 1:12 | 30.00 ft | 30.10 ft | 4.76 degrees | 2 |
| 36 in | 1:12 | 36.00 ft | 36.12 ft | 4.76 degrees | 3 |
| 30 in | 1:10 | 25.00 ft | 25.12 ft | 5.71 degrees | 2 |
| 30 in | 1:16 | 40.00 ft | 40.08 ft | 3.58 degrees | 2 |
Ramp questions
What does a 30 inch rise at 1:12 produce?
Leave the rise at 30 in and the ratio at 12. Rise reads 2.50 ft · 0.76 m. Run reads 30.00 ft · 9.14 m. Ramp length reads 30.10 ft · 9.18 m. Angle reads 4.76 degrees · 8.33 percent. Runs reads 1. Landings reads 2. The note reads Meets 2010 ADA 405.2. A 1:12 ramp is the steepest slope allowed for new work.
How many landings does 36 inches of rise need?
Change the rise to 36 in and leave the ratio at 12. Run reads 36.00 ft · 10.97 m. Ramp length reads 36.12 ft · 11.01 m. Angle still reads 4.76 degrees · 8.33 percent. Runs reads 2. Landings reads 3. Each run is limited to 30 inches of rise, so 36 inches is two runs, and the landing count is one more than the runs.
What if the ratio is 10 on a 30 inch rise?
Set the rise back to 30 in and the ratio to 10. Run reads 25.00 ft · 7.62 m. Ramp length reads 25.12 ft · 7.66 m. Angle reads 5.71 degrees · 10.00 percent. Runs reads 1. Landings reads 2. The note reads Steeper than 1:12. Existing-site Table 405.2 allows this only up to 6 inches of rise, and this rise is over that limit.
Does a 6 inch rise at 1:10 fit the existing-site table?
Set the rise to 6 in and leave the ratio at 10. Run reads 5.00 ft · 1.52 m. Ramp length reads 5.02 ft · 1.53 m. Angle reads 5.71 degrees · 10.00 percent. The note reads Steeper than 1:12. Existing-site Table 405.2 allows this only up to 6 inches of rise, and this rise is within that limit.
What does a gentler 1:16 ratio do?
Set the rise to 30 in and the ratio to 16. Run reads 40.00 ft · 12.19 m. Ramp length reads 40.08 ft · 12.22 m. Angle reads 3.58 degrees · 6.25 percent. Runs reads 1. Landings reads 2. The note reads Gentler than 1:12, so it meets 2010 ADA 405.2. The standard does not require the steepest slope.
What if the ratio box is cleared?
Clear the ratio and leave the rise at 30 in. Rise reads 2.50 ft · 0.76 m. Run reads Enter a ratio. Ramp length reads Enter a ratio. Angle reads Enter a ratio. Runs reads 1. Landings reads 2.
Does this page size the landings or the handrails?
No. 2010 ADA 405.7.3 calls for a landing at least 60 inches long, and 405.7.4 calls for a 60 by 60 inch landing where the direction changes. 405.8 calls for handrails when a run rises more than 6 inches. 405.5 calls for 36 inches of clear width, and 405.3 limits cross slope to 1:48. Those are stated here and are not separate result lines.