Use this workshop calculation to turn measured dimensions and the selected construction convention into a cut, spacing, fit, or material-planning value.

Riser height (cm)

Riser height in centimeters.

Check whether a stair riser height falls in the ideal 17 to 18 cm range and report its deviation in centimeters. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Is ideal riser

True when the riser height is between 17 and 18 cm inclusive.

Deviation from ideal (cm)

Deviation from the ideal 17 to 18 cm range in centimeters, zero inside the range.

• Nominal dimensions, kerf, moisture movement, hardware clearances, wall squareness, and manufacturer instructions can change the required shop dimension. Measure the actual assembly and test critical joints on scrap before cutting finished material.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Complement the calculated dimension with a physical story stick, dry fit, or full-size layout. Follow the hardware, coating, adhesive, or machine manufacturer's limits where they differ from a rule of thumb.

• Tread Depth Check

  Check whether a stair tread depth falls in the ideal 28 to 29 cm range and report its deviation in centimeters.

• Handrail Diameter Check

  Check whether a handrail diameter lies in the comfortable 42 to 48 mm grip range and report the deviation.

• Treppen Sicherheitsregel

  Compute the German stair safety-rule dimension as tread going plus riser height; this is a planning metric, not a structural or code check.