Our Ramp Slope Calculator helps you plan an accessible ramp or check one you already have. Enter the total rise to get the ramp run you need at your chosen slope, with intermediate landings, total footprint, and handrail requirements worked out. Switch to check mode, enter the rise and run of an existing ramp, and the calculator tells you the actual slope and whether it meets the 1:12 maximum.
It is useful for architects planning entrances and plinths, interior designers working on level differences inside buildings, students learning accessibility norms, and site teams verifying a ramp before it is cast.
What Is the 1:12 Rule?
The 1:12 rule says that for every 1 unit a ramp rises, it must run at least 12 units horizontally. A 1 metre plinth therefore needs 12 metres of ramp. In percentage terms that is a gradient of 8.33%, which is the steepest slope a wheelchair user can manage independently over a sustained climb. Gentler presets of 1:16 and 1:20 are more comfortable and are preferred wherever space allows.
The slope alone does not make a ramp compliant. Long ramps need level resting platforms: a landing of at least 1500 mm at the top and bottom of every run, and another every 9 metres of horizontal run. Handrails are required on both sides wherever the rise exceeds 150 mm, set at 760 to 900 mm above the ramp surface and extended 300 mm beyond each end. The clear width should be at least 1200 mm, the surface must be slip resistant, and the cross slope should stay gentle so wheelchairs do not drift sideways.
The basic formulas used are:
Required Run = Total Rise × 12 (for the 1:12 maximum)
Actual Slope = Available Run ÷ Total Rise, expressed as 1:x
A ramp that rises 0.6 m needs 7.2 m of run at 1:12. The same rise over only 5 m of run gives a 1:8.3 slope, which is too steep and fails the check. That quick comparison is exactly what the check mode of this calculator does for you.
Where Can You Learn Accessibility and Building Codes Properly?
Ramp design sits inside the larger subject of barrier-free design and building codes, which every practising architect is expected to know. ASDAV courses in architecture, interior design, Revit, and BIM teach accessibility planning, NBC norms, estimation, and drawing-based quantity work the way it is done on real projects. Explore the ASDAV courses and masterclasses to build these skills step by step.
