Use this construction calculation for preliminary quantity, geometry, material, load, or coverage planning when dimensions and units have been measured consistently.

Total horizontal run (m)

Required number input.

Number of treads

Required integer input.

Divide total horizontal stair run by the number of equal treads; excludes nosing projections and landings. 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]

Equal tread depth (m)

The resulting equal tread depth returned as a number.

• A quantity estimate or simplified engineering formula is not a building-code check, stamped design, manufacturer approval, or site inspection. Material properties, tolerances, waste, moisture, workmanship, loads, local conditions, and code requirements can change the result.
• 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.

Verify dimensions on site, use current product data and local code requirements, include an explicit waste or safety allowance where appropriate, and obtain qualified structural, electrical, plumbing, or geotechnical review when required.

• Stair Riser Height

  Divide total vertical rise by the number of equal risers; check local stair-code bounds separately.

• Drain Slope Fall Per Foot

  Convert a drain's horizontal run in feet and specified fall in inches per foot into total fall.

• Theoretical Rafter Length

  Find the straight-line rafter length between eave and ridge from horizontal run and vertical rise; excludes overhang and cuts.