Drainage Slope Calculator
Calculate drainage grade, total fall, slope ratio, angle, pipe sections and pipe cost for a straight run.
Default project preview
1 % slope
Total fall
1 ft
Fall per 10 units
1.2 in per 10 ft
Slope angle
0.57°
Ending elevation
99 ft
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Slope percent = total fall ÷ horizontal run × 100. Ratio = run ÷ fall. Pipe length uses the sloped hypotenuse plus the entered allowance.
FAQ
Drainage Slope Calculator questions
What does a one-percent slope mean?+
It means one unit of fall for every one hundred equal units of horizontal run.
Can a drain be too steep?+
Yes for some systems. Excessive grade can create installation or flow problems, so follow the applicable design standard.
Should pipe length equal horizontal run?+
The sloped pipe is slightly longer than the horizontal run, and connections or routing usually require additional allowance.