Pipe Slope Calculator

Inputs

Calculation mode

Use slope mode when the required pitch is known. Use invert mode when start and end elevations are measured.

Pipe run length (L)

Horizontal run length along the pipe layout, not the sloped pipe centerline length.

Pipe slope (S)

Slope as fall divided by horizontal run times 100. 2.083% equals 1/4 in per foot.

End direction

Gravity drains usually fall from start to end. Use rise only for an elevation comparison or non-gravity layout.

Start invert elevation (E1)

Invert elevation at the upstream or starting point. The datum can be arbitrary if only the relative change matters.

Default result

Fall over run(dE)

0.127m

Pass

falls from start to end

Also computed

End invert elevation(E2)30.353m

Slope percent(S)2.083%

falls from start to end

Slope per foot(pitch)0.25in/ft

falls from start to end

Pitch ratio(1:n)481:n

1:48.0

Pipe angle(theta)1.193°

Run length used(L)6.096m

Method notes 3 notes

Geometry: fall = run x slope percent / 100, and slope percent = fall / run x 100.
Useful conversions: 1/8 in/ft = 1.04%, 1/4 in/ft = 2.08%, and 1/2 in/ft = 4.17%.
This is a layout calculator only. Final drainage and plumbing work still needs adopted code, local amendments, fixture loads, pipe material, cleanouts, venting, traps, site elevations and inspection requirements.