Wheelchair Ramp Calculator - Part M & BS 8300 Gradient & Length

Under Approved Document M Vol 2 §1.26 Table 1, the steepest gradient allowed is 1:12 (8.3%), but only on a short flight with a going of up to 2m (rise up to 166mm). A 1:15 gradient is allowed for a going up to 5m (rise up to 333mm) and 1:20 for a going up to 10m (rise up to 500mm); you can interpolate in between. A gentler gradient is always preferable as it is easier for wheelchair users to navigate independently. No single flight may have a going greater than 10m or a rise of more than 500mm.

Intermediate landings are required whenever the per-flight rise cap is reached: 1:12 allows 166mm rise per flight, 1:15 allows 333mm, 1:20 allows 500mm. Per AD M Vol 2 §1.26, the foot and head landings must be at least 1200mm long (§1.26(h)), but any INTERMEDIATE landing must be at least 1500mm long (§1.26(i)), and the ramp surface width must be at least 1500mm between walls/upstands/kerbs. Where the ramp has three flights or more, or a wheelchair user cannot see from one end to the other, the intermediate landings must instead be 1800mm x 1800mm passing places (§1.26(j)). Top and bottom landings are always required regardless of ramp length.

Approved Document M Vol 2 §1.26(e) requires a ramp surface width of at least 1500mm between walls, upstands or kerbs (BS 8300-2 agrees). Where two-way wheelchair traffic is expected, 1800mm is recommended. (1200mm is the minimum for the foot/head landing length, not the ramp width.)

Yes. AD M Vol 2 §1.26(l) requires a handrail on both sides of a ramp. Per §1.37, the top of the handrail is 900–1000mm above the ramp pitch line (900–1100mm where it runs along a landing), it must be continuous across the flights and landings, and it must extend at least 300mm horizontally beyond the top and bottom of the ramped access. A circular handrail should be 32–50mm in diameter with a slip-resistant finish, set with a clearance of between 50mm and 75mm from any adjacent wall. (The older 40–50mm diameter / 50–60mm clearance figures come from the withdrawn BS 8300:2001 and have been superseded.)

Temporary or portable ramps can be used for existing buildings where a permanent ramp is not feasible. They must still meet a maximum gradient of 1:12 and be stable, slip-resistant, and have raised edges. However, for new buildings, Part M requires permanent ramped access. Temporary ramps are not considered compliant for Building Regulations approval on new-build projects.

The ramp going (sloped length) is the rise you need to overcome multiplied by the gradient ratio: Going = Rise x Gradient Ratio. For example, a 600mm rise needs a going of 7200mm (7.2m) at 1:12, 9000mm (9m) at 1:15, or 12000mm (12m) at 1:20. This calculator does that sum for you, then adds the landings AD M Vol 2 §1.26 requires: at least 1200mm at the foot and head of the ramp (§1.26(h)) plus at least 1500mm for every intermediate landing (§1.26(i)), or 1800mm x 1800mm passing places once the ramp needs three flights or more (§1.26(j)). So the total built length is always longer than the sloped going alone, and shallower gradients need proportionally more going but fewer landings.

AD M Vol 2 Table 1 states ramp steepness as a ratio, not an angle, but the three permitted gradients convert as follows: 1:20 (the gentlest, preferred where space allows) is about 2.9 degrees or 5%; 1:15 is about 3.8 degrees or 6.7%; and 1:12 (the steepest permitted, short flights only) is about 4.8 degrees or 8.3%. These figures come from the trigonometric relationship angle = arctan(1 / gradient ratio), and percentage = (1 / gradient ratio) x 100. There is no separate degree or percentage limit in Approved Document M itself, only the ratio-and-going table this calculator uses.

Not for a permanent, Part M-compliant ramp. 1:12 is the steepest gradient Approved Document M Vol 2 Table 1 allows, and only for a short flight with a going of up to 2m; there is no exception for a tight site. Where the available space genuinely cannot fit a 1:12 ramp within the 2000mm total-rise limit for ramped access (AD M Vol 2 §1.26(d)), the usual alternatives are a platform lift, a powered ramp, or regrading the approach, and these should be discussed with Building Control or an access consultant before committing to a design. Short portable threshold ramps sold for carer-assisted, non-independent use sometimes quote steeper ratios such as 1:6 or 1:8, but these are a different product category from a Building Regulations-compliant access ramp and are not a substitute for one.

Not technically, though the phrase is still in everyday use. The Disability Discrimination Act 1995, which is where the term comes from, was repealed on 1 October 2010 and replaced by the Equality Act 2010 (legislation.gov.uk). The Equality Act places a duty on service providers to make reasonable adjustments for disabled people, but it does not itself set a ramp gradient, landing size or handrail height. Those technical figures come from Approved Document M and BS 8300-2:2018, both used throughout this calculator, so a ramp described as 'DDA compliant' today really means it meets AD M and BS 8300.

UK rules. This calculator applies Approved Document M Vol 2 Table 1 and BS 8300-2:2018, which allow 1:20 for long ramps, 1:15 for medium ramps, and 1:12 only for short flights up to 2m going. The US Americans with Disabilities Act (2010 ADA Standards §405, US Access Board) is different: it sets one flat maximum running slope of 1:12 (8.3%) regardless of ramp length, requires a landing at least every 762mm (30 inches) of rise, and caps cross slope at 1:48. If your project is in the UK, use the AD M figures on this page; the ADA figures do not apply here.