Drainage Pipe Slope Calculator

Work out the total fall over a drain run from a chosen slope, and check it against the minimum grade for the pipe size. Pick 1/8", 1/4", or 1/2" per foot and enter the run.

Drain Run

Run Length (ft)

Applied Slope

Pipe Size (in)

For min-slope check

Code Family

Fall

Enter run length to calculate

Common minimums (IPC): pipes 2-1/2" and smaller need 1/4" per foot; 3" and larger may run at 1/8" per foot. Verify against the governing plumbing code for your jurisdiction.

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