Staircase Calculator
Calculate the number of steps, riser height, tread depth, and total stringer length for a staircase. Ensures compliance with building code guidelines.
Did this tool work for you?
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.
- 1
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
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.
Learn more from an authoritative source:
WikipediaRoofing Calculator
Calculate the total roof area for gable, hip, or flat roofs. Get roofing material quantities in squares, sheets, and tiles with waste allowance.
Concrete Calculator
Calculate the volume of concrete needed for slabs, footings, columns, or steps. Get results in cubic metres, cubic feet, and bags of ready-mix.
Paint Calculator
Calculate how many litres of paint you need to cover walls, ceilings, or a room. Accounts for doors, windows, coats, and paint coverage rate.
Flooring Calculator
Calculate how many square metres of flooring you need for any room. Supports rectangular and L-shaped rooms, with waste percentage.
Tile Calculator
Calculate how many tiles you need for a floor or wall. Enter room dimensions and tile size to get tile count, boxes needed, and grout quantity.
Fence Calculator
Calculate the number of fence posts, rails, pickets, and panels needed for any fence length. Supports common picket and panel fence styles.
Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →