| Primary value | 1:12 (8.33%) |
| Applies to | Wheelchair-accessible ramps · Building entrance ramps · Public building accessibility ramps |
| Exceptions | Preferred slope (better UX) → 1:20 (5%) |
| Curb ramps (short) → 1:10 allowed | |
| Measured as | Vertical rise per unit horizontal run. 1:12 means 1 m rise for every 12 m of run. |
| Source | NBC 2016 + IS 4963 — Part 4 + IS 4963 Section 5 ✓ Verified |
1:12 is the steepest slope that an unassisted wheelchair user can self-propel up. Anything steeper requires assistance and effectively excludes independent mobility-aid users from the building.
Most public buildings provide 1:14 to 1:16 for comfort. New BIS-compliant projects target 1:18 to 1:20 where space allows.