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

Horizontal run (ft)

Required number input.

Fall per foot (in/ft)

Required number input.

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

Total drain fall (in)

The resulting total drain fall returned as a number.

• Drainage and flashing dimensions depend on catchment, rainfall, roof or surface geometry, outlet capacity, material, climate, and local detailing. Confirm slopes and terminations against the complete water-management design.
• 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.

• Excavation Slope Ratio

  Horizontal run per unit vertical rise of an excavation slope; this geometric ratio is not a safe-slope determination.

• Gutter Slope Fall

  Calculate elevation drop along a gutter from horizontal length and design slope per meter.

• Lumber Cost Per Board Foot

  Calculate lumber price per board foot from total lumber cost and the board-foot quantity priced on the same nominal or actual dimension basis.