DM COMPOSITES TOOL

Stairway Calculator

Calculate indicative stairway requirements and review suitable FRP stair solutions for your project.

DM Composites Tool

Stairway Calculator

Enter the stair geometry to calculate slope, stringer length, riser height, going and the dimensional checks listed in the supplied AS 1657 stairway worksheet.

CSV connected Stairways Design AS1657 1(Slope).csv · stair geometry and dimensional compliance checks

Stairway Geometry

Vertical Height

Horizontal Run / Breadth

Clear Width Between Stringers

Geometry Definition

Height is the total vertical rise. Breadth is the total horizontal run between the lower floor and upper landing.

Tread Arrangement

Number of Treads

no.

Tread Depth (TD)

How the CSV is interpreted

Risers = treads + 1

Riser height R = height ÷ risers

Going G = breadth ÷ treads

Use a whole-number tread count. The calculator can recommend the closest count that satisfies all displayed dimensional checks.

Recommended Stair Arrangement

Recommended Tread Count -

Enter the stair geometry to view the closest compliant tread arrangement.

Overall Result -

Slope Angle -

Stringer Span -

Risers / Treads -

Stairway Summary

Item	Calculated Value	How It Is Used
Total Height	-	Total vertical rise.
Total Breadth	-	Total horizontal run.
Clear Width	-	Width between the inside edges of the stringers.
Riser Height (R)	-	Height divided by the number of risers.
Going (G)	-	Breadth divided by the number of treads.
Tread Depth (TD)	-	Physical tread depth entered by the user.

Dimensional Check Results

Check	Actual	Displayed Requirement	Status
Slope Angle	-	20° to 45°	-
Clear Width	-	At least 600 mm	-
Tread Count	-	Whole number, at least 1	-
Riser Height (R)	-	130 ≤ R ≤ 225 mm	-
Going (G)	-	215 ≤ G ≤ 355 mm	-
Comfort Combination	-	540 ≤ 2R + G ≤ 700 mm	-
Tread / Going Combination	-	G ≤ TD + 30 mm	-

Uniformity Requirement

All risers and all goings in the same flight shall be of uniform dimensions within a tolerance of ±5 mm.

Tread-by-Tread Schedule

Indicative set-out values measured from the base of the stair.

Level	Cumulative Rise	Cumulative Run	Description

Indicative Stairway Diagram

Criteria Used by This Website Calculator

20°–45°Slope angle

130–225 mmRiser height

215–355 mmGoing

540–700 mm2R + G

G ≤ TD + 30Tread relationship

Need confirmation for a project?

Send the calculated stairway geometry to the DM Composites team for review.

Important Engineering Note

This calculator is an indicative dimensional tool. It does not replace the full requirements of AS 1657, structural stringer and tread design, landings, handrails, connections, access assessment or project-specific engineering review.

NEED HELP?

Not sure which clip setup is right for your project?

Speak with the DM Composites team for product guidance, project support and help confirming the right fastening solution for your FRP grating application.