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Construction & DIYGenerated accuracy model review: 2026-05-06
Stair Calculator accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- 1. **Number of Risers** = Total Rise / Target Riser (Rounded to nearest whole number). 2. **Actual Riser Height** = Total Rise / Number of Risers. 3. **Total Run** = (Number of Risers - 1) × Tread Depth (usually 10 inches).
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Total Rise: 108 in
- Target Riser: 7.5 in
Expected outputs
- Number of Steps: 14
- Exact Riser Height: 7.71 in
- Total Run: 10.83 ft
Known limitations
- Assumes a standard 10-inch tread run. Does not account for nosing overhang or landing platforms.
Assumptions
- Total rise and target riser are measured in inches and must be positive.
- The calculator uses a standard 10-inch tread run and rounds to the nearest whole riser count.
- Local stair code rules vary, so the result should be checked against your jurisdiction before building.
Unit handling
- Total Rise accepts values in in.
- Target Riser accepts values in in.
- Exact Riser Height is displayed in in.
- Total Run is displayed in ft.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current stair-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Stair Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.