One step: measure it before you buy
A single step is the case where an inch matters most. At 6 inches high the ramp is 6 ft; at 7.75 inches, the tallest riser the IRC allows in a house, it is 7.75 ft. A 7 inch step sits between them at 7 ft.
Handrails are required when the rise is more than 6 inches. So a 6 inch step is just inside the line and a 7 inch step is over it: the example on this page needs handrails on both sides.
Ramp length for 1 step by riser height
Steps are not all the same height, so find your riser in the first column or measure the total rise.
| Riser height | Total rise | 1:12 ramp | 1:16 ramp | 1:20 ramp | Runs | Footprint at 1:12 |
|---|---|---|---|---|---|---|
| 6 in | 6 in | 6 ft | 8 ft | 10 ft | 1 | 11 ft |
| 6.5 in | 6.5 in | 6.5 ft | 8.67 ft | 10.83 ft | 1 | 11.5 ft |
| 7 in | 7 in | 7 ft | 9.33 ft | 11.67 ft | 1 | 12 ft |
| 7.25 in | 7.25 in | 7.25 ft | 9.67 ft | 12.08 ft | 1 | 12.25 ft |
| 7.5 in | 7.5 in | 7.5 ft | 10 ft | 12.5 ft | 1 | 12.5 ft |
| 7.75 in | 7.75 in | 7.75 ft | 10.33 ft | 12.92 ft | 1 | 12.75 ft |
7 inch rise at each slope
| Slope | Ramp length (run) | Along the surface | Percent | Angle | Runs | Footprint with landings |
|---|---|---|---|---|---|---|
| 1:12 (ADA maximum) | 7 ft | 7.02 ft | 8.3% | 4.8° | 1 | 12 ft |
| 1:16 | 9.33 ft | 9.35 ft | 6.3% | 3.6° | 1 | 14.33 ft |
| 1:20 | 11.67 ft | 11.68 ft | 5.0% | 2.9° | 1 | 16.67 ft |
Is a shorter ramp too steep?
| Ramp length | Slope | Percent | Angle | Within 1:12? |
|---|---|---|---|---|
| 3 ft | 1:5.1 | 19.4% | 11.0° | No, 4 ft too short |
| 5 ft | 1:8.6 | 11.7% | 6.7° | No, 2 ft too short |
| 7 ft | 1:12 | 8.3% | 4.8° | Yes |
| 11 ft | 1:18.9 | 5.3% | 3.0° | Yes |
Other step counts (7 inch risers)
| Steps | Rise | 1:12 ramp | Runs | Footprint |
|---|---|---|---|---|
| 2 steps | 14 in | 14 ft | 1 | 19 ft |
| 3 steps | 21 in | 21 ft | 1 | 26 ft |
| 4 steps | 28 in | 28 ft | 1 | 33 ft |
| 5 steps | 35 in | 35 ft | 2 | 45 ft |
Know the height in inches? See a ramp for 6 inches of rise, or the ramp length and slope guide. The stair calculator works out riser heights from a total rise.
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 of a ramp do I need for 1 step?
Measure the total height. One step 7 inches high is 7 inches, which needs a 7 ft ramp at 1:12 (1 foot of ramp per inch of rise). A 7.75 inch step needs 7.75 ft.
Does a ramp over one step need handrails?
It depends on the height. Under the ADA figures handrails are needed when the rise is more than 6 inches, so a 6 inch step does not need them and a 7 inch step does.
How high is 1 step?
Usually 6 to 7.75 inches, at 6 to 7.75 inches a riser. Count every riser, including the last one up onto the porch or threshold, or simply measure from the ground to the door sill.
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.