Stair Riser Calculator
Estimate equal stair risers, actual riser height, and total tread run from floor rise and a target riser height.
Your result
Review your calculated values below.
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How to use this calculator
- Enter your values in the labeled fields, keeping the displayed units.
- Choose Calculate or press Enter in a single-line field.
- Review the result and the assumptions below before using it.
Formula and method
Risers = ceiling(total rise / target riser). Actual riser = total rise / risers. Treads = risers − 1; run = treads × tread depth.
Worked example
A 280 cm rise with a target maximum of 18 cm uses 16 risers at 17.5 cm and 15 treads. At 28 cm per tread, the run is 420 cm.
What the result assumes
Assumes one straight flight with the upper floor serving as the top landing. Local stair rules, headroom, landings, and structural design require separate checks.
Common question
Why is there one fewer tread than riser?
This layout uses the upper floor as the final walking surface. Different landing arrangements may change the tread count.