How the ramp calculator works
A ramp trades height for distance. The gradient says how much height is gained for each unit of horizontal travel, so the run is simply the rise divided by the gradient. A 1:12 slope climbs 1 cm for every 12 cm of run, or one inch per foot, which is 8.33%. Gentler slopes are easier to push a wheelchair up but need more room.
Run = rise ÷ gradient · Landings = ⌈run ÷ max run⌉ − 1 · Footprint = run + (landings + 2) × landingLong ramps are split into sections with flat rest landings in between, because nobody should have to push uphill without a break. The footprint also counts a level landing at the top and the bottom, where a user turns, opens the door or stops before the path. The sloped length, found with Pythagoras, is the actual surface you will build or deck.
Worked example
A front door sits 60 cm above the path. At 6%, the maximum used in Germany, the ramp needs a run of 0.60 ÷ 0.06 = 10 m. With a limit of 6 m between landings, that is two sections and one intermediate landing of 1.5 m. Add top and bottom landings and the ramp occupies 10 + 3 × 1.5 = 14.5 m of length, a figure that often forces a switchback layout on a small front garden. The sloped surface is 10.02 m long, so a 1.2 m wide ramp has 12 m² of deck. The same 24 in step built to the ADA 1:12 maximum needs 24 ft of run and no intermediate landing, since the rise stays under 30 in; with 5 ft landings at each end it takes 34 ft.
Gradients and how much run they need
| Gradient | Run per 10 cm of rise | Run per inch of rise | Where you meet it |
|---|---|---|---|
| 1:8 (12.5%) | 0.80 m | 8 in | Portable ramps with a helper only |
| 1:12 (8.33%) | 1.20 m | 12 in | ADA maximum; UK only for goings up to 2 m |
| 8% (1:12.5) | 1.25 m | 12.5 in | France, short ramps up to 2 m long |
| 6% (1:16.7) | 1.67 m | 16.7 in | Germany DIN 18040 maximum |
| 5% (1:20) | 2.00 m | 20 in | France general rule; UK up to 10 m going |
Rules that shape a ramp
In the US, the ADA Standards cap public ramps at 1:12, with no more than 30 in of rise per run, a clear width of at least 36 in, landings at least 60 in long and handrails on both sides when the rise exceeds 6 in. Germany's DIN 18040 limits slopes to 6% with a 1.5 m landing after every 6 m and a usable width of 1.2 m. England's Approved Document M allows 1:20 for goings up to 10 m but only 1:12 for goings up to 2 m. Private homes are not always bound by these standards, yet they describe what users can actually manage. Always confirm the rules with your local building authority, and follow its code for guards, handrails and supports on any raised ramp.
Planning tips
- Measure the real rise. Ground often slopes away from the door; take the height where the ramp will actually start, not beside the step.
- Keep the cross slope flat. Sideways tilt makes a wheelchair veer; ADA limits it to 1:48.
- Add edge protection. A curb or rail along open sides stops a wheel or cane slipping off.
- Choose a grippy surface. Brushed concrete, grit-coated decking or rubber matting stays usable when wet or icy.
- Use the door swing. The top landing must be large enough to open the door without rolling backwards.
Frequently asked questions
How long does a wheelchair ramp need to be for 3 steps?
Three 7 in steps make a 21 in rise, so a 1:12 ramp needs 21 ft of run, plus a 5 ft landing at the top and the bottom. At 1:20 the run grows to 35 ft.
What is the ADA ramp slope?
The ADA maximum is 1:12, one inch of rise per foot of run, or 8.33%, with at most 30 in of rise before a level landing.
How long should a ramp be for a 60 cm rise?
At 6% it needs 10 m of run, at 1:12 it needs 7.2 m and at 5% it needs 12 m, before adding landings.
How often does a ramp need a landing?
Under ADA, after every 30 in of rise, which is 30 ft at 1:12. Germany's DIN 18040 requires a landing after every 6 m of ramp.
How wide should a wheelchair ramp be?
ADA requires at least 36 in (91 cm) between handrails; DIN 18040 asks for 1.2 m. Wider ramps are easier to use with a walker or a helper.
Last reviewed: 2026-09-27 · How we calculate