Calculate drainage slope, total fall, percent grade, inches per foot, elevation drop, and pipe pitch for drain lines, yard drains, sewer drains, storm drains, French drains, and gravity drainage planning.
Total fall from slope:
The calculator multiplies drain run by slope to estimate the required elevation drop.
Slope from fall:
The calculator divides total fall by drain run to calculate inches per foot, percent grade, feet per foot, and degrees.
Run from fall:
The calculator divides available fall by target slope to estimate how long the drain can run.
Elevation check:
The calculator compares start and end elevations to calculate actual drainage fall and slope.
A drainage slope calculator helps estimate the slope needed for gravity drainage, yard drainage, stormwater lines, sewer drains, French drains, and surface drainage.
It can help compare total fall, percent grade, inches per foot, drain run, start elevation, end elevation, and target slope.
Your result shows estimated drainage slope, total fall, percent grade, and drain run. Use this as a planning estimate only. Actual drainage design can depend on local code, soil conditions, pipe material, pipe size, water volume, outlet location, freezing depth, and site grading.
Drainage slope is how much a drain line, surface, or pipe drops over a certain run. It is often shown as percent grade or inches per foot.
Divide total fall by total run. Multiply by 100 to get percent grade, or multiply feet per foot by 12 to get inches per foot.
A 2% slope means the drain drops 2 feet over 100 feet of run. That is about 1/4 inch per foot.
No. This calculator gives a planning estimate. Final drainage slope should be checked against code, site grade, pipe size, drainage volume, and local conditions.