Staircase Calculator
Calculate the number of steps, riser height, tread depth, and total stringer length for a staircase. Ensures compliance with building code guidelines.
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How to use this calculator
Rise = total floor-to-floor height. Riser height (R) should be 150–220 mm. Tread depth (T) should be 220–350 mm. Comfort rule: 2×R + T between 600 and 640 mm.
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Enter the total floor-to-floor height (rise) in millimetres.
- 2
Set a target riser height — the calculator finds the nearest whole number of steps.
- 3
Check the actual riser height and adjust tread depth to satisfy the 2R+T comfort rule.
- 4
Always verify against your local building code before construction.
Frequently asked questions
What is the ideal riser height for stairs?
Most building codes specify 150–220 mm, with 175–185 mm considered most comfortable for adults. Shallower risers require more floor space; steeper risers are harder on the knees and less safe for children and the elderly.
What is the 2R + T formula?
2 × riser height + tread depth should equal 600–640 mm for comfortable stair geometry. Example: riser 180 mm, tread 260 mm: 2×180 + 260 = 620 mm ✓. This ensures each step feels natural — not too steep or too shallow.
What is a nosing overhang?
The nosing is the edge of the tread that extends beyond the riser below it, typically 20–30 mm. It provides a small amount of extra foothold and is required by most building codes for interior stairs.
Staircase Calculator — Risers, Treads & Stringer Length
How to use the staircase
Use this staircase to he number of steps, riser height, tread depth, and total stringer length for a staircase. Enter your values above and get your result in seconds. The tool is free, works on all devices, and keeps your data private — nothing is stored or shared.
How the staircase works
The staircase calculator uses standard formulas used in building projects, renovation planning, and material ordering. Enter your inputs, and the tool calculates the result instantly in your browser. No server-side processing means your data stays on your device. Results update in real time as you change inputs.
Stair geometry and building codes
Building codes vary by country but share similar principles: risers must be consistent (no variation greater than 5 mm across the flight), handrails are required for more than 3 steps, minimum width is typically 900 mm for residential stairs, and headroom clearance of at least 2,000 mm is needed throughout the stair flight.
Stringer types and materials
Open stringer: treads are visible from the side — suits floating or contemporary stair designs. Closed stringer: treads sit in housings routed into the stringer — traditional look, stronger. Materials: LVL (laminated veneer lumber) for straight stairs; solid timber for traditional; steel for industrial/floating designs. The stringer carries the load, so sizing is structural — consult an engineer for spans over 3 m.
Staircase: how it works
Construction estimation tools save time and reduce material waste by calculating exact quantities before you buy. This tool uses standard industry formulas for accurate estimates across common building and renovation tasks.
Who uses this tool?
Contractors, DIY homeowners, quantity surveyors, and architects use it to generate material lists before requesting quotes. It supports better project planning and reduces the risk of costly underestimates.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →