Wheelchair Ramp Calculator

Measure the vertical rise first, then multiply by the slope ratio. At the ADA maximum of 1:12, a 2 ft rise needs a 24 ft horizontal run — that is the whole “ramp length calculator” rule: run = rise × 12. As an angle that is 4.76° and as a grade 8.33%. You also need a level landing at the top and bottom (60 in minimum each under ADA §405.7), so the straight-line footprint is 24 ft of run plus 10 ft of landings = 34 ft. This wheelchair ramp slope calculator does the same math for any rise and any standard.

The ADA Standards (§405.2) set the maximum running slope at 1:12 — 4.76° or 8.33% grade — for new construction and alterations. An ADA compliant ramp calculator must also enforce the companion rules: no more than 30 in of rise per run (§405.6), at least 36 in of clear width (§405.5), cross slope no steeper than 1:48 (§405.3), handrails on both sides when the rise exceeds 6 in (§405.8), and level landings at the top and bottom of every run, at least 60 in long and at least as wide as the ramp — 60×60 in clear where the ramp changes direction (§405.7).

A 1:12 slope is arctan(1/12) = 4.76°, and 1 ÷ 12 = 8.33% grade. That is the core of any 1:12 slope calculator or wheelchair ramp angle calculator. The number most people forget is the deck: the actual ramp surface is the hypotenuse, slightly longer than the horizontal run. For a 24 ft run at 1:12 the deck is 289 in long — about 0.35% longer — which is why this page works as a ramp slope ratio calculator that reports both.

Three standard 7 in steps = 1 ft 9 in of rise. At 1:12 the ramp run calculator gives 21 ft of run, plus two 60 in landings, for a 31 ft straight footprint — a single run, since 1 ft 9 in is under the 30 in per-run limit. As a portable ramp length guide: a manual wheelchair needs the same 21 ft of portable ramp; a mobility scooter at a typical maker limit of about 6° (1:9.5) needs 16 ft 7.5 in. Anything shorter than these is steeper than the device can safely handle.

Only in existing sites, buildings and facilities where space limitations make 1:12 impossible (ADA §405.2, Table 405.2). The table caps it: 1:10 where the rise is at most 6 in — so a 6 in step needs a 5 ft run at 5.71° — and 1:8 where the rise is at most 3 in — a 3 in threshold needs a 2 ft run at 7.13°. Anything steeper than 1:8 is prohibited. On ADA ramp requirements residential note: the ADA itself covers public and commercial facilities, not private homes, but most builders still use 1:12 as the home safety benchmark, and many local codes adopt it for dwellings.

Run = rise × ratio. A 3 ft rise at 1:12 exceeds the 30 in per-run limit, so it splits into 2 runs of 1 ft 6 in rise each — 18 ft of run per run, 36 ft of run total. With 3 landings (top, bottom and one between the runs) at 60 in each, the straight footprint is 51 ft long. Tight on space? The switchback ramp calculator layout folds the two runs side by side: about 28 ft long × 6 ft 4 in wide, with a 60×60 in turn landing.

UK Approved Document M (Table 1) limits the gradient by flight going: 1:12 for goings up to 2 m, interpolating down to 1:20 for goings up to 10 m, with at most 500 mm of rise per flight and 1200 mm landings. So a 0.50 m rise takes 3 flights at 1:12, each with a 2 m going, plus 4 landings of 1.2 m — a 10.80 m straight footprint. A 0.30 m rise fits in 2 flights at 1:12 with a 1.8 m going each. Use the UK mode above and this ramp gradient calculator picks the steepest compliant gradient automatically.

The 1:14 ramp gradient is the AS 1428.1 maximum for ramps: 4.09°, 7.14% grade. A 150 mm rise therefore needs a 2.10 m run, with 1200 mm landings and 1000 mm minimum clear width. Shorter rises get their own categories: the 1:10 step ramp (rise at most 190 mm — a 190 mm step needs 1.90 m) and the 1:8 threshold ramp (rise at most 35 mm — a 35 mm threshold needs 0.28 m). Where space allows, a 1:20 ramp slope (5%) is the gentler planning choice.

Under the ADA ramp landing requirements: at least 60 in long in the direction of travel and at least as wide as the ramp — and a clear 60×60 in square wherever the ramp changes direction, which handrails and posts may not intrude into. UK Approved Document M and AS 1428.1 both require 1200 mm landings. Wheelchair ramp landing size is what makes or breaks a switchback: the turn landing is a maneuvering space, not leftover deck.

Follow your scooter maker’s manual first — mobility scooter ramp slope limits vary, but many makers rate sustained climbs around 6° (about 1:9.5). At 1:9.5 a 1 ft 9 in rise needs 16 ft 7.5 in of portable ramp (6.01°). Fixed ramps are a different matter: code still caps them at 1:12 (US), 1:14 (Australia) or the Part M table (UK) regardless of what the scooter could climb.

Wheelchair ramp width requirements: the ADA requires 36 in minimum clear width, measured between handrails where provided (§405.5). Australia requires 1000 mm clear between handrails (AS 1428.1); the UK requires 900 mm clear for ramps on approach routes (Approved Document M). Wider is always more comfortable — 48 in is a common upgrade for two-way or assisted use.

The ADA ramp handrail requirements: handrails on both sides when the rise is greater than 6 in (ADA §405.8, §505) — so virtually every real ramp except tiny threshold ramps needs them. They must be 34–38 in high, continuous the full length of the run, with 12 in extensions at the top and bottom. Australia requires handrails on both sides for ramps over 190 mm rise (and where the ramp exceeds 1900 mm); the UK requires a handrail on at least one side for stepped and ramped approaches.