If you’re fitting a threshold ramp at your front door, back step, or a commercial entrance, getting the gradient right is one of the most important decisions you’ll make. Too steep, and the ramp becomes hard or even dangerous to use. Too shallow, and it may not fit the space you have available. Here’s what you need to know about safe and recommended gradients for threshold ramps.
Why gradient matters
A threshold ramp’s gradient is the ratio of its rise (height) to its run (length). This determines how much effort is needed to get up it, whether it’s under your own power, with the help of a carer, or using a wheelchair or mobility scooter.
Get the gradient wrong and you risk a ramp that tips wheelchairs backwards, causes scooters to lose traction, or simply proves too tiring to use every day. For anyone with limited strength or stamina, even a slightly steep ramp can turn a simple doorway into a daily obstacle.
The general rule of thumb
For most domestic threshold ramps, a gradient of 1:12 is considered the standard safe minimum. This means for every 1 cm of rise, you need at least 12 cm of ramp length. So a threshold that’s 4 cm high would need a ramp at least 48 cm long to meet this ratio.
Where space allows, a gentler gradient such as 1:15 or 1:20 is even better, particularly for anyone who self-propels a wheelchair or has reduced upper body strength. The shallower the gradient, the less effort required, though this does mean a longer ramp.
What British Standards recommend
BS 8300, the British Standard covering accessible design, sets out gradient recommendations based on the rise of the ramp:
- For rises up to 150mm, a gradient of 1:12 is generally acceptable
- For greater rises, shallower gradients are recommended, with 1:15 or 1:20 preferred wherever there’s enough room
- Very short rises, under around 50mm, can sometimes use steeper gradients over a short distance, though this should still be approached carefully
These are guidelines rather than strict legal limits for domestic properties, but they’re a sensible benchmark to work to, and they become more important for commercial premises where accessibility obligations under the Equality Act 2010 apply.
Practical considerations beyond the numbers
Gradient calculations are a good starting point, but a few other factors affect whether a threshold ramp will actually work well in practice:
Available space. A steep threshold with limited approach space is one of the most common challenges we see. Sometimes the ideal 1:12 or 1:15 gradient simply won’t fit, and a modular ramp with a slight bend or an alternative layout is needed to make the most of the space available.
Who’s using it. A gradient that’s manageable for someone using a walking frame may still be tough going for a wheelchair user propelling themselves. It’s worth thinking about everyone who’ll regularly use the ramp, not just the steepest case.
Surface and weather. Even a well-judged gradient can feel steeper in wet or icy conditions. A textured, slip-resistant surface makes a real difference alongside getting the angle right.
Edge transitions. A ramp is only as good as its start and end points. Smooth transitions at the top and bottom prevent trip hazards and make the whole ramp feel safer to use.
Getting it right first time
Because gradient depends on both the height of your threshold and the space available, it’s worth having it assessed properly rather than guessing. At Access Allround, we survey each property individually and recommend a gradient and ramp length that balances safety with what will actually fit your doorway.
If you’re dealing with a high threshold, a tight approach, or you’re just not sure what’s achievable, get in touch.