Wheelchair Ramp Calculator
This wheelchair ramp calculator works out how long a ramp must be for a given rise and how many runs and landings it needs. Enter the total rise, choose the ADA 1:12 slope, the German DIN 18040 limit of 6%, a gentler slope, or your own ratio, and the wheelchair ramp calculator returns the ramp length in meters and feet, the slope and angle, the number of runs, the intermediate landings, and the total footprint.
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The Wheelchair Ramp Calculator is part of our Structural collection. Browse more structural to size, convert, and check your work alongside this tool.
What the wheelchair ramp calculator does
A wheelchair ramp trades height for length: the gentler the slope, the longer the ramp. Accessibility standards set the steepest slope a wheelchair user can manage and how far a ramp may run before a level landing gives a rest. The wheelchair ramp calculator multiplies the rise by the slope ratio for the ramp length, splits it into runs under the chosen standard, and adds the landings so you can see the full space the ramp needs.
Wheelchair ramp slope and length rules
The horizontal length is the rise times the ratio. Each standard then limits each run:
The number of runs is the total rise divided by the maximum rise per run (ADA) or the total length divided by 6 m (DIN), rounded up. One landing sits between each pair of runs, and both standards also need a level landing at the top and the bottom. The calculator reports the slope in percent and degrees, the sloped surface length, and the area of the ramp surface for ordering decking or concrete.
Wheelchair ramp calculator example
A porch 900 mm high with an ADA 1:12 ramp:
The ramp with its middle landing is 12.32 m long, and with top and bottom landings the footprint is about 15.4 m. A 600 mm rise under DIN 18040 at 6% needs 10 m of ramp in 2 runs with a 1.5 m landing, 11.5 m in total.
How to use the ramp length calculator
Measure the total rise from the ground where the ramp starts to the top of the threshold or door landing, in millimeters (25.4 mm per inch). Choose the standard: ADA 1:12 for the US, DIN 18040 at 6% for Germany, or a gentler 1:16 or 1:20 for users who self-propel or for long ramps. Enter the clear width between handrails to check it against the standard. Press Calculate.
Reading the wheelchair ramp length
The ramp length is the horizontal distance, the figure you need for a site plan. The sloped surface is slightly longer and is the one to use when ordering decking or nosing. If the result does not fit the site, a switchback layout with a turning landing, at least 1,500 by 1,500 mm, folds the same ramp into a shorter space. Never shorten a ramp by making it steeper than 1:12: users in manual chairs and their helpers need the gentle slope to climb and to control the descent.
When to use an ADA ramp calculator
- Planning a ramp to a front door or porch
- Checking a contractor quote for length and landings
- Designing ramps for shops and public entrances
- Comparing a straight and a switchback layout
- Ordering materials for a wooden or concrete ramp
Common wheelchair ramp calculator mistakes
- Measuring the rise to the wrong point. Measure to the top of the door threshold.
- Forgetting landings. They add 1.5 m each.
- Building steeper than 1:12. It is unsafe for many users.
- Ignoring cross slope. Keep the ramp level side to side.
Tips for a wheelchair ramp slope
- Choose 1:16 or 1:20 for long ramps if space allows.
- Add a level landing in front of every door.
- Check local building rules before you build.
ADA ramp calculator vs DIN 18040 ramp rules
The ADA allows 8.33% and limits each run by its rise, so a 30-inch rise is the longest single run: 9.12 m. DIN 18040 in Germany caps the slope at 6% and each run at 6 m, so the same 760 mm rise needs 12.67 m in three runs. Both require handrails on both sides, edge protection, and a landing in front of the door. Where space is too short for a ramp, steps with a lift may be the answer, and the stair calculator lays out a comfortable step for the same rise.
Wheelchair ramp length for wooden and concrete ramps
Wooden ramps need joists sized for the span and a slip-resistant surface; plan the railing posts and infill with the baluster spacing calculator so the gaps stay below the code limit. A poured ramp is a sloped slab: multiply the ramp surface area by the slab thickness and add the landings, then order the volume with the concrete calculator. A broom finish across the slope gives grip in wet weather.
Wheelchair ramp length chart: ADA 1:12 and DIN 18040 6%
| Total rise | ADA 1:12 run | ADA runs | DIN 18040 6% run | DIN runs |
|---|---|---|---|---|
| 150 mm (5.9 in) | 1.8 m (5.91 ft) | 1 | 2.5 m | 1 |
| 300 mm (11.8 in) | 3.6 m (11.81 ft) | 1 | 5 m | 1 |
| 450 mm (17.7 in) | 5.4 m (17.72 ft) | 1 | 7.5 m | 2 |
| 600 mm (23.6 in) | 7.2 m (23.62 ft) | 1 | 10 m | 2 |
| 760 mm (29.9 in) | 9.12 m (29.92 ft) | 1 | 12.67 m | 3 |
| 900 mm (35.4 in) | 10.8 m (35.43 ft) | 2 | 15 m | 3 |
| 1200 mm (47.2 in) | 14.4 m (47.24 ft) | 2 | 20 m | 4 |
Wheelchair ramp slope, ratio, and angle
| Slope | Ratio | Angle | Run per 100 mm of rise |
|---|---|---|---|
| 8.33% | 1:12 | 4.76° | 1.20 m |
| 6.25% | 1:16 | 3.58° | 1.60 m |
| 6% | 1:16.7 | 3.43° | 1.67 m |
| 5% | 1:20 | 2.86° | 2.00 m |
Wheelchair Ramp Calculator FAQ
How long should a wheelchair ramp be?
At the ADA slope of 1:12, 12 units of length for every unit of rise: 1 m of ramp per 83 mm of rise, or 1 foot per inch. A 600 mm rise needs a 7.2 m ramp.
What is the ADA ramp slope?
1:12, or 8.33%, at most, with no more than 30 inches (760 mm) of rise in one run before a level landing.
How often does a ramp need a landing?
Under the ADA after every 760 mm of rise; under DIN 18040 after every 6 m of ramp length. Both also need landings at the top and bottom.
How wide should a wheelchair ramp be?
At least 36 inches (915 mm) clear between handrails under the ADA and 1,200 mm under DIN 18040.