CrewMeasure

Drain Slope Calculator

Total fall for a drain pipe run, from length and slope.

Slope this drain run at 0.25 in/ft over — ft.

Pipe run source

Pull the fitting-adjusted pipe footage from the plumbing calculator, or override manually.

Run source

Already ran the plumbing calculator for this job? Use Active project to reuse that pipe footage automatically. Otherwise switch to Manual and type your own run length.

Chained pipe footage

Run the plumbing calculator first to prefill pipe run length.

Slope inputs

IPC Table 704.1 sets the minimum by pipe size: 1/4 in per ft for 2-1/2 in and smaller, 1/8 in per ft for 3 in to 6 in, 1/16 in per ft for 8 in and larger.

Slope this drain run at 0.25 in/ft over — ft.

Slope at

Drain slope estimate

Warnings

  • INFO No pipe footage is saved in the active project yet, so the manual run length is being used.
  • ERROR Enter a pipe run length greater than zero.
  • INFO Slope defaults to 1/4 in per ft. 1/4 in per ft is the IPC Table 704.1 minimum for horizontal drainage pipe 2-1/2 in and smaller. Larger pipe has flatter published minimums -- 1/8 in per ft for 3 in to 6 in, 1/16 in per ft for 8 in and larger -- so match the slope to the pipe size.

Detail values

Pipe run used
— ft

Assumptions

  • Slope: 0.25 in per ft (IPC Table 704.1 minimum: 1/4 for pipe 2-1/2 in and smaller, 1/8 for 3 in to 6 in, 1/16 for 8 in and larger)

Included: total fall over the run.

Not included: labor, verification against manufacturer or local-code specifics beyond the reference table used, material waste from cutting.

Formula details
  • Total fall: pipeRunLength x slope

    1/4 in per ft is the IPC Table 704.1 minimum for horizontal drainage pipe 2-1/2 in and smaller. Larger pipe has flatter published minimums -- 1/8 in per ft for 3 in to 6 in, 1/16 in per ft for 8 in and larger -- so match the slope to the pipe size. Editable for any other slope.

Material List

About this calculator

Pull the fitting-adjusted pipe footage from the plumbing calculator, or enter your own run length.

FAQ

Can I use this without the plumbing calculator?

Yes. Switch to manual and enter the pipe run length directly.

Where does the 1/4 in per ft default come from?

It's the standard IPC drain slope. It's editable for other slopes (e.g. 1/8 in per ft for larger-diameter pipe).