Staircase Calculator
Calculate staircase dimensions to SANS 10400-M. Find riser height, tread depth, number of steps, stringer length, and materials. Includes spiral staircase, handrail, and disabled ramp tools.
Quick Calculator Get a fast estimate
mm
mm
Number of steps
13
Riser height
207,7 mm
Tread depth (going)
270 mm
Total run (horizontal)
3,51 m
Stair angle
37,6°
2R + T (comfort rule)
685 mm (should be 550–700)
SANS 10400-M compliant
Yes
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How to Use the Staircase Calculator
Enter the total floor-to-floor height and preferred tread depth. The calculator finds the optimal number of steps and checks compliance with SANS 10400-M building regulations.
The Extended Calculator adds stringer dimensions and material cost estimates. The Professional Calculator covers spiral staircases, handrail quantities, and disabled access ramps to SANS 10400-S.
Need more detail?
Extended Calculator More options, charts, and scenario comparison
mm
mm
mm
Step dimensions
207,7 mm riser
Riser height
207,7 mm
Tread depth
270 mm
2R + T
685 mm (ideal 550–700)
Stair angle
37,6°
Total horizontal run
3,51 m
Headroom clearance
Min 2000 mm (SANS 10400-M)
Staircase Design Formulas
Number of steps = ⌈Total height ÷ Max riser⌉
Actual riser = Total height ÷ Number of steps
Total run = Number of steps × Tread depth
Stringer length = √(Total rise² + Total run²)
Comfort formula: 2R + T = 550–700 mm
SANS 10400-M Staircase Requirements
| Dimension | Private stairs | Public stairs |
|---|---|---|
| Max riser height | 220 mm | 190 mm |
| Min riser height | 130 mm | 130 mm |
| Min tread depth | 240 mm | 250 mm |
| Min stair width | 750 mm | 1000 mm |
| Min headroom | 2000 mm | 2100 mm |
| Handrail height | 900 mm | 900–1000 mm |
Need full precision?
Professional Calculator Complete parameters, sensitivity analysis, and detailed breakdown
mm
mm
Spiral staircase
225 mm riser
Rotation per step
30°
Step width
600 mm
Tread at walk-line
289 mm
Min diameter (SANS)
1500 mm (private), 1800 mm (commercial)
Frequently Asked Questions
SANS 10400-M: private — max riser 220mm, min tread 240mm; public — max riser 190mm, min tread 250mm. Min headroom 2000mm. Use the comfort formula 2R + T = 550–700mm. All risers in a flight must be equal within 5mm.
Steps = ceil(total height ÷ max riser). For 2700mm at max 220mm: ceil(2700/220) = 13 steps. Actual riser = 2700/13 = 207.7mm — all steps must be this exact height. Never mix riser heights in one flight.
2×Riser + Tread should equal 550–700mm for comfortable walking. A 180mm riser with 280mm tread gives 2×180+280 = 640mm — ideal. Too steep (<550) strains legs going up; too shallow (>700) feels like walking on a ramp.
Stringer = √(rise² + run²). After cutting step notches, min residual depth must be 175mm. Use 250×50mm pine or 300×50mm hardwood. For widths over 1m, add a central stringer.
SANS 10400-S: max 1:12 (8.3%). For a 500mm step, ramp = 500×12 = 6000mm long. Min width 1200mm. Handrails 900mm high on both sides. Non-slip surface required. Landing every 9m of ramp.