How it works

A useful distinction

Lower risers can need more space

At fixed floor-to-floor rise and tread run, adding a riser lowers each step but adds one tread to the standard layout. Compare both riser height and total run; a gentler stair may exceed the available footprint.

Checking stair geometry against the intended layout

Total rise, tread dimensions, and the number of risers work together to determine a stair layout. Review whether the upper floor acts as the final landing in the selected mode. Mounting and headroom inputs add geometric constraints but do not establish compliance with every building requirement. Verify the actual layout and applicable local rules before using an estimate for construction.

Straight stair geometry: formula and assumptions

Risers = ceil(total rise/preferred maximum). Actual riser = total rise/risers.

This layout assumes one fewer tread than risers and does not certify compliance with local building codes.

Known rise, run & riser count: formula and assumptions

Riser height=total rise/N; tread run=total run/(N−1).

Assumes one fewer tread than risers. Dimensions do not certify building-code compliance.

Mounting, supports & headroom: formula and assumptions

Headroom = (opening − mounting offset) × riser / tread run − floor thickness.

Standard offset is zero; flush offset is one tread run. The geometry references finished floors and the line through tread noses. It is not a structural stringer cutting plan.

Worked example

Using the Straight stair geometry example:

Inputs

Total rise (inches): 108
Preferred maximum riser (inches): 7.75
Tread run (inches): 10

Method

Risers = ceil(total rise/preferred maximum). Actual riser = total rise/risers.

Result

Example result

Risers: 14

Actual riser height: 7.71 in

Treads: 13

Total run: 130 in

These are illustrative inputs. Change the values to explore a different scenario.

Formula references

References explain the underlying methods; they do not imply endorsement or individual professional review of Finflo.

Common questions

Is there always one fewer tread than risers?

The standard layout has N − 1 treads. The flush-mount option adds a tread at landing height, giving N modeled treads.

Does the headroom result certify a safe or compliant staircase?

No. It describes clearance over the modeled nose line. Structural design, cutting details and local building requirements need separate verification.

Prepared by Finflo. See our methodology and editorial policy.

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