Fall Per Foot Calculator

The Fall Per Foot Calculator helps users determine the slope or gradient of a surface, especially in applications involving drainage, plumbing, or construction. This measurement tells you how much vertical drop occurs over a specific horizontal distance—typically expressed as inches of fall per foot of horizontal run. This calculator is essential for ensuring proper slope in piping systems, driveways, ramps, and drainage channels. It allows both homeowners and professionals to evaluate if the slope meets functional or regulatory standards.

This tool belongs to the construction and civil engineering calculators category and supports practical decisions in real-world projects like pipe installations and landscape grading.

formula of Fall Per Foot Calculator

Fall Per Foot = Total Vertical Fall / Total Horizontal Run

Where:
Fall Per Foot = Slope of the surface (inches per foot or unitless ratio)
Total Vertical Fall = Change in elevation (in inches or feet)
Total Horizontal Run = Length along the base (in feet)

When using inches and feet:

Fall Per Foot (in/ft) = (Vertical Fall in inches) / (Horizontal Run in feet)

If both dimensions are in feet:

Fall Per Foot = Vertical Fall (ft) / Horizontal Run (ft)
To convert to inches per foot, multiply the result by 12.

This formula is widely used in pipe laying, surface grading, and ramp design to ensure gravity-based flow or safe incline levels.

Common Slope Reference Table

This table allows for quick reference, especially when verifying standard drainage or accessibility slope requirements.

Example of Fall Per Foot Calculator

Suppose you're installing a drainage pipe that drops 3 inches over a 12-foot run.

Using the formula:
Fall per Foot = Vertical Fall / Horizontal Run
Fall per Foot = 3 in / 12 ft = 0.25 in/ft

This means for every foot of pipe, the drop is 0.25 inches. This is a common slope used for ensuring proper water drainage.

Most Common FAQs