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Vriksai Timber Intelligence

Stair Geometry ToolStaircase Rise, Run & Pitch Calculator

Design a comfortable, code-compliant staircase. Calculate equal riser heights, going, pitch angle and the Blondel comfort check from your floor-to-floor rise, verified against UK, India, US or European standards.

Equal RisersGoing + PitchBlondel CheckCode Compliance TablePDF Report
SG

Stair Geometry Tool

Staircase Rise, Run & Pitch Calculator

Stair Dimensions
mm

Finished floor to finished floor.

mm

Horizontal length available. 0 = auto from Blondel.

mm

Comfortable ~175mm.

OK
Stair Geometry Results
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risers
Number of Risers
-
mm
Riser Height
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mm
Going (Tread)
-
degrees
Pitch Angle
ParameterValueStandardCheck
Stair Calculation
About Stair Geometry Tool
A comfortable, safe staircase follows precise relationships between riser height and tread depth (going). Too steep and it is tiring and dangerous; too shallow and it wastes space. This tool divides your floor-to-floor rise into equal risers, calculates the matching going, and checks the result against the Blondel comfort formula and your chosen building standard - showing each check in a clear pass/fail table.
Where Is This Used?
Staircase DesignJoinery + CarpentryBuilding ComplianceRenovationArchitectural LayoutLoft Conversions
Formulas & Standards
Number of risers = round(Total rise / Target riser)Actual riser = Total rise / Number of risers (all equal)Number of treads = Risers - 1Blondel formula: 2 x Riser + Going = 550-700 mmPitch angle = arctan(Riser / Going), keep under ~42 deg
Frequently Asked Questions
Why must all risers be exactly equal?
People climb stairs by feel, not by looking. Even a few millimetres difference between risers breaks that rhythm and is a major trip hazard - building codes require all risers in a flight to be equal. That is why you divide the total rise by a whole number of risers rather than picking a round riser height and leaving an odd step.
What is the Blondel formula?
Devised by French architect Francois Blondel, it relates riser and going to match the human stride: twice the riser plus the going should fall between about 550 and 700mm (590-650 is ideal). It is the single best check for stair comfort and is embedded in building codes worldwide.
How do the country standards differ?
They set different maximum risers and minimum goings. UK Part K allows steeper domestic stairs (riser up to ~220mm); US IRC demands a deeper tread (min 279mm going) and lower riser; India's NBC and European norms sit in between. This tool checks your stair against whichever standard applies to your project.
ResourcesView the formulasFormula Library
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