The straight stair tool uses a floor-to-floor height and either a going or a horizontal run. Choose the input mode that matches the dimensions you have.
- Total rise
- The vertical distance between finished floor levels. It is not the sloping length of the flight.
- Going
- The horizontal advance from one step to the next. It is not a tread-board cut size and does not add a separately specified nosing.
- Horizontal run
- Use the measurement convention shown in the app. Check the lower and upper reference points against your intended construction before using a site measurement.
- Units
- Use metric lengths or feet and inches. Angles and percentage gradient are different quantities.
Pro² suggests a riser count from its calculation preferences. The riser control lets you explore a different count when calculation access is available. Review the resulting rise height and going together.
Risers describe vertical divisions. Physical treads describe the surfaces below the upper floor; the two counts are not interchangeable.
The result includes rise height, going, run, pitch and stringer length. Compare the table with the side view and step detail before saving the calculation.
After editing a dimension, press Calculate again. An earlier result may remain visible when an input is invalid; check that the result belongs to the dimensions you intend to use.
The Headroom & Opening section accepts the upper-floor thickness and the vertical headroom you require. It estimates an opening from the stair geometry; it does not inspect an existing opening or select a local requirement for you.
Check the actual floor edge, beams, finishes and measurement references separately. This overview does not provide a worked opening size or a construction layout.
- Enter your dimensions in the iPhone app; this website has no calculator input form.
- Recalculate after edits and inspect validation messages.
- Save under a useful job name and reopen it when measurements change.
- Before setting out or cutting, verify the project geometry, supports and applicable requirements.
Can I calculate in the browser?
No. Use Pro² for iPhone through the App Store link. This page describes the tool.
Does the calculation approve my stair for construction?
No. Project-specific measurement, structural design and compliance checks remain necessary.
- Can I calculate in the browser?
- No. Use Pro² for iPhone through the App Store link. This page describes the tool.
- Does the calculation approve my stair for construction?
- No. Project-specific measurement, structural design and compliance checks remain necessary.
Measurements, units and material terms
All stair calculators