Trench Length Calculator for Downspout Underground Extensions: This calculator estimates the trench length required to install an underground downspout extension, based on the roof area, the rainfall intensity, and the slope of the surrounding soil.

Trench Length Calculator for Downspout Underground Extensions

Roof Area (square feet):

Rainfall Intensity (inches per hour):

Downspout Size (inches):

Slope of Surrounding Soil (inches per foot):