Stair calculator: rise, run and steps
Enter the total rise, the maximum riser height and the tread depth; it also checks the 2 risers + 1 tread comfort rule.
Loading the tool…
Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter total rise, maximum riser height and tread depth (going).
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Risers = total rise ÷ max riser, rounded up. Actual riser = rise ÷ risers. Treads = risers − 1. Total run = treads × tread depth. Stringer line = √(rise² + run²). Angle = arctan(riser ÷ tread).
Example
Inputs: Total rise = 2,700 mm, Maximum riser height = 180 mm, Tread depth (going) = 280 mm. Result: Risers (steps): 15; Actual riser height: 180 mm; Treads: 14.
Limits and caveats
- Your local building code sets the maximum riser, minimum tread and handrail rules; check it before building.
- Assumes a straight flight with no landing or turn.
Questions about this tool
What is the 2R + G rule?
An old comfort rule: twice the riser plus the tread depth should be roughly 600 to 660 mm, close to a normal stride.
Why one tread fewer than risers?
The top step is the upper floor itself, so it needs no separate tread.
What riser height is comfortable?
In homes 150 to 180 mm is common; higher steps get tiring, especially for children and older people.