What the result helps you understand
A stair can look reasonable in a sketch while failing one of the interacting riser, going, proportion or flight-length limits. Showing each check separately makes the geometry easier to correct.
Access & Safety
AS 1657 Stair Geometry Calculator
Check riser, going, the 2R+G proportion, flight riser count and calculated stair angle for a proposed industrial stair flight.
“I know the rise available for the platform stair. Does my proposed riser and going combination fit the AS 1657 geometry screens?”
Core formulae
Industrial stair geometry screen
Proportion check
2R + GStair angle
θ = tan⁻¹(R / G)Total rise
H = R × number of risersApproximate run
Run ≈ G × (risers − 1)The calculator checks R = 130–225 mm, G = 215–355 mm, 2R+G = 540–700 mm and 2–18 risers in the flight.
Simple arrangement sketch
Riser and going
1
Stair flight geometry
Enter one consistent riser and going for the flight, plus the total number of risers.
Results
AS 1657 stair-geometry screen
2R + G640 mm
Within 540–700 mm screen.
Stair angle32.74 °
Within 20–45° slope screen.
Total vertical rise2,160 mm
Approximate horizontal run3,080 mm
Assumes the top landing forms the final level, so run ≈ G × (risers − 1).
Riser checkWithin range
130–225 mm
Going checkWithin range
215–355 mm
Flight riser-count checkWithin range
Whole number from 2 to 18 risers.
The entered stair geometry passes these five numerical screens
Riser, going, 2R+G, flight riser count and calculated slope are within the ranges checked here. Continue with the rest of the access-system design.
Geometry-only boundary
Not checked: landings, headroom, stair width, handrails, guardrails, openings, nosings, slip resistance, load capacity, access location, environmental conditions or whether stairs are the appropriate means of access.
Job-file record
Save the calculation, not just the number.
Copy a permalink that reloads these inputs, or download a PDF record with inputs, visible results, assumptions, a sensitivity note, date and disclaimer.
Know where the quick calculation stops
This calculator does not check landings, headroom, stair width, handrails, guardrails, openings, nosings, slip resistance, load capacity, access location or the complete AS 1657 access system.
Important boundary
A calculator can show the arithmetic. It cannot establish every requirement that applies.
Confirm the actual equipment, loading, materials, condition, jurisdiction, contractual requirements, standard edition and current project documentation before using the result for design, repair, testing or lifting decisions.
Ask an engineer about this calculation →