How to use the Stair Calculator
Size a simple straight stair using rise, riser height, tread depth and stringer geometry.
Calculation formula
Riser count = ceil(total rise / target max riser); each riser = total rise / riser count; tread count = risers − 1 for an upper landing; stringer ≈ hypot(total rise, horizontal run).
Recommended steps
- Enter values using the units shown beside each field.
- Review whether the example assumptions match your situation.
- Run the calculator and compare the key metrics.
- Use the source data or official rates when precision matters.
Known limitations
Generic straight-flight sizing only. Verify local building codes and account for nosing, finish thickness and landings.
Open the calculator →