Measurement & Project Planning calculator
Stair Calculator
Explore stair riser count, actual riser height and total run from floor-to-floor rise, target riser and tread depth.
Explore stair riser count, actual riser height and total run from floor-to-floor rise, target riser and tread depth. Use finished project dimensions and product-specific data where available rather than generic defaults. The most sensitive assumption here is riser/tread constraints. Stair geometry is safety-critical and regulated in many locations. Use the result to explore a layout, then verify riser, going/tread, headroom, landings and guarding against the rules that apply to the project.
What you need to enter
The Stair Calculator uses the following project information to calculate the result.
- Total rise
- Target riser height
- Tread depth
Calculator result
Riser count, actual riser height and total run
How the Stair Calculator works
To produce riser count, actual riser height and total run, the Stair Calculator applies layout estimator; final stairs must comply with applicable building rules. The engine is configured for riser count, actual riser height and total stair run, not as a generic text estimate. Check riser/tread constraints, since an incorrect value there can materially change the result.
Stair Calculator worked example
Stair Calculator example: For a 2,600 mm total rise and a target riser near 175 mm, a 15-riser layout gives an actual riser of about 173.3 mm. With 250 mm treads and 14 goings, the basic horizontal run is about 3.5 m before landings or nosings. The worked figure becomes more useful when riser/tread constraints is taken from the real product or site rather than a generic default.
Important calculation assumptions
For riser count, actual riser height and total stair run, stair geometry is safety-critical and regulated in many locations. Use the result to explore a layout, then verify riser, going/tread, headroom, landings and guarding against the rules that apply to the project.
Frequently asked questions
Which starting measurements make the Stair Calculator more reliable?
The quality of the result starts with the inputs. Measure finished floor-to-floor rise and choose the intended tread depth. Use the target riser only as a layout starting point. They are used here to estimate riser count, actual riser height and total stair run.
Can a small change in riser/tread constraints materially affect the Stair Calculator result?
The key uncertainty in the Stair Calculator concerns riser/tread constraints. Stair geometry is safety-critical and regulated in many locations. Use the result to explore a layout, then verify riser, going/tread, headroom, landings and guarding against the rules that apply to the project.
Is the Stair Calculator suitable for final design decisions?
Use the layout to compare riser counts and total run, then verify riser, going/tread, headroom, landings and guarding against the building rules that apply before construction. That is the practical way to carry the Stair Calculator result into the next step.