How to Measure Wheelchair Ramp Length Safely

A ramp that is only a little too steep can make a doorway difficult to use every day. It can also affect safety for a wheelchair user, carer or support worker. Knowing how to measure wheelchair ramp requirements starts with the vertical rise, then turns that measurement into the right ramp length, width and landing space for the location.

Start with the rise, not the ramp

The rise is the vertical height from the lower surface to the higher surface. For example, this may be the distance from a driveway or path up to a front door threshold, from a deck down to the garden, or from the ground into a vehicle.

Place a straight, level board or spirit level from the upper surface out over the lower surface. Measure straight down from the underside of the level board to the lower surface. Record this measurement in millimetres. Measuring from an uneven point, or following the slope of the ground with a tape measure, will give you the wrong result.

If the area has more than one step or changes in level, measure the total rise that the ramp needs to cover. Also check whether the surface under the ramp is level and firm. A portable ramp may bridge the height difference, but it cannot safely compensate for soft soil, loose gravel or a sloping base.

How to measure wheelchair ramp length

Ramp length is determined by the gradient, or how much the ramp rises over its horizontal length. A gentler gradient requires a longer ramp, but it is generally easier and safer to use.

For a commonly used 1:14 gradient, allow 14 units of ramp length for every one unit of rise. If the rise is 100 mm, the ramp needs at least 1,400 mm of usable ramp length. A 150 mm rise needs 2,100 mm, while a 300 mm rise needs 4,200 mm.

Use this simple calculation:

Rise in millimetres x 14 = minimum ramp length in millimetres

A 1:14 gradient is a useful starting point for many access situations and reflects the maximum gradient commonly associated with compliant access ramps. However, the right answer depends on the user, the wheelchair, the available space and whether the ramp is part of regulated building work. A manual wheelchair user propelling independently may need a gentler slope. A person using a heavy power wheelchair, or a carer assisting someone up the ramp, may also benefit from extra length.

Some short portable ramps are marketed for steeper gradients. They can be suitable for small thresholds in particular situations, but a shorter ramp is not automatically the better option. Steeper ramps increase the effort needed to ascend, reduce control on descent and may create grounding issues where the ramp meets the ground or threshold.

When comparing ramp lengths, check the usable length rather than relying only on a product name. A folding ramp's overall length, folded size and loading length can differ.

Check the approach and departure angles

A ramp can be the correct calculated length and still be unsuitable if the wheelchair catches at either end. This is more likely with a low footplate, anti-tippers, a long wheelbase power chair or a scooter.

Check the transition from the ground onto the ramp and from the ramp onto the upper surface. The ramp should sit securely without a lip, gap or sudden change in level. Measure the threshold itself as well. A high, rounded or narrow door sill may need a purpose-designed threshold ramp rather than a longer channel ramp.

Measure the width your wheelchair actually needs

Do not choose a ramp based only on the width of a doorway. Measure the widest part of the wheelchair or mobility device, including hand rims, armrests, joystick controls, wheel guards or any accessories that remain in place during use.

Then allow practical clearance on both sides. A ramp that technically fits the wheels but leaves no room for steering corrections can feel unsafe, particularly outdoors or when a carer is assisting. For channel ramps, measure the wheel track: the centre-to-centre distance between the wheels, as well as the tyre width. The channels must align with the wheels and be wide enough for the tyres.

A solid-surface ramp provides more flexibility than channels where several wheelchairs, walkers or prams will use the same entrance. Channel ramps can be lighter and easier to handle, but they require more accurate positioning and are not suitable for every device. Three-wheel scooters, narrow castors and wheelchairs with unusual wheel spacing need especially careful checking.

The doorway also needs to be wide enough for the user to pass through once the ramp is installed. Consider door swing and handles. An inward-opening door may leave too little room to manoeuvre on a small landing, while an outward-opening door can conflict with the ramp position.

Allow room for landings and turning

A ramp is more than the sloping section. The wheelchair user needs a stable, level area at the top and bottom to stop, open a door, turn or reposition safely. Measure these spaces before choosing a ramp, especially at front entrances, decks and internal thresholds.

For a simple straight ramp to a door, look at the clear level area outside the door and the available area at the bottom. If the ramp changes direction, a level turning platform may be needed. Long permanent ramps may also require intermediate landings, handrails, edge protection and drainage, depending on the design and applicable requirements.

This is where site conditions matter. A ramp that reaches from the driveway to the door may be the correct length on paper but may cross a path, block a gate, obstruct a hose tap or leave no safe place for a person to wait while opening the door. Measure the full route, not just the step.

Measure for the type of ramp you need

Portable ramps are useful for temporary access, travel, a single threshold or occasional vehicle loading. They need to be secure at both ends and rated for the combined weight of the wheelchair, user and any person assisting. For power chairs and scooters, this total can be much higher than expected.

A threshold ramp is generally intended for a small change in level. Measure the threshold height and its profile, then check the ramp's stated height range and overall depth. The depth matters because it controls the gradient.

For vehicle access, measure from the ground to the vehicle floor or loading point with the vehicle parked on a level surface. Also measure the available loading length and the clearance around the rear opening. Suspension height, kerbs and uneven car parks can change the angle considerably, so allow a safety margin rather than measuring only in the most favourable location.

A permanent modular or built ramp may be the better option where access is used daily, the rise is substantial or the user cannot safely manage a steeper portable ramp. These installations should be assessed for the site, intended use and relevant Australian building and accessibility requirements. Local council, strata or landlord approval may also be required before work begins.

Record the details before you shop

A few clear measurements make it much easier to compare options or ask for guidance. Record the rise, available horizontal space, wheelchair width, wheel track if considering channels, threshold shape, door opening direction and the combined load. Photos taken from the side and front of the access point can also help show surface conditions and obstacles.

It is worth checking the wheelchair's manual for overall dimensions and weight, particularly if accessories, a pressure cushion, headrest or power assist unit are fitted. Equipment can change the practical clearance and loading requirements.

If the ramp will be used by a child, a person with changing mobility needs or more than one household member, plan for the equipment likely to be used over time rather than only the chair currently at the door.

When to seek professional advice

For a permanent ramp, a complex entrance, a substantial height difference or a ramp funded through the NDIS, seek advice from an occupational therapist, building professional or qualified access provider. They can assess propulsion ability, transfer needs, turning space, falls risk and any compliance requirements that a tape measure alone cannot address.

For portable ramps, specialist product guidance can help match the ramp to the wheelchair, not just the step height. Wheelability can assist with practical measurements and product considerations so you can choose equipment that supports safer, more confident access at home and when out in the community.

A good ramp should make the route feel easier, not like another obstacle to manage. Measure carefully, allow room for the whole journey and choose the gentlest practical gradient for the person who will use it most.