Staircase Calculator
Estimate staircase risers and total run, with an illustrative dimension check based on entered rise and tread.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Calculate a stair layout from total floor-to-floor rise, target riser height and tread depth. The reference check compares only riser height and tread depth with fixed thresholds; it does not verify a complete design or local building-code compliance. Confirm plans with the relevant building authority or a qualified professional.
Worked example
calculated with the default values below
Total rise (floor to floor) 108 in · Desired riser height 7 in · Tread depth 10 in Number of risers 16 · Number of treads 15 · Actual riser height 6.75 in · Total run 150.0 in · Total run 12.5 ft · Basic dimension reference Meets the calculator reference
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
R = ceil(H ÷ r₀); r = H ÷ R; G = (R − 1) × t; reference = (r ≤ 7.75) and (t ≥ 10)
- H
- total rise (in)
- r₀
- target riser (in)
- R
- risers
- r
- actual riser (in)
- t
- tread depth (in)
- G
- total run (in)
Risers = ceiling(total rise ÷ target); actual riser = total rise ÷ risers; treads = risers − 1; total run = treads × depth. Reference checks are not code approval.
Frequently asked questions
How does the calculator choose the riser count?
It rounds the riser count up so the actual riser height does not exceed your requested target. For a 108 in total rise and a 7 in target, it uses 16 risers at 6.75 in each. The reference checks only actual riser height up to 7.75 in and tread depth of at least 10 in; local rules and other stair requirements still need review.