2" Diameter Min Code Fall: 1/4" per foot 2.08% Grade (1:48) IPC Table 704.1

2" Drain Pipe Slope & Fall Calculator

Under model plumbing codes (IPC & UPC), a horizontal 2" gravity drainage pipe must be installed with a minimum fall of 1/4" per foot (2.08% pitch or 1:48 slope ratio) to ensure self-scouring velocity (2.0 ft/s). Part of our master Drain Pipe Slope Calculator and Flow Rate Calculator suite.

Presets:

Slope Profile 1.67% Grade

Calculated Drain Slope

2.08% 1 : 48.0

Equivalent Fall: 1/4" per foot (2.50" per 10 ft)

Total Fall (Drop) 5.00 in

Horizontal Run 20.00 ft

Fall per Foot 0.250 in/ft

Actual Cut Length 20.00 ft

Your drain pipe drops 5.00 inches over a 20.00 ft horizontal run. This produces a 2.08% slope (1 : 48.0 ratio), dropping 0.250 inches per foot (2.50 inches per 10 feet).

Code Elevation Drop Schedule

2" Drain Pipe Fall vs. Run Length Chart

Exact elevation drop required over distance at standard 1/4" per foot slope (2.08% grade).

Horizontal Run (Ft)	Required Drop (Inches)	Ft-Inches Format	Metric Fall (mm)	Code Compliance Status
5 ft	1.25 in	0' 1.3"	31.7 mm	✓ Meets IPC/UPC
10 ft	2.50 in	0' 2.5"	63.4 mm	✓ Meets IPC/UPC
15 ft	3.75 in	0' 3.8"	95.1 mm	✓ Meets IPC/UPC
20 ft	5.00 in	0' 5.0"	126.8 mm	✓ Meets IPC/UPC
30 ft	7.50 in	0' 7.5"	190.2 mm	✓ Meets IPC/UPC
40 ft	10.00 in	0' 10.0"	253.6 mm	✓ Meets IPC/UPC
50 ft	12.50 in	1' 0.5"	317.0 mm	✓ Meets IPC/UPC
75 ft	18.75 in	1' 6.8"	475.5 mm	✓ Meets IPC/UPC
100 ft	25.00 in	2' 1.0"	634.0 mm	✓ Meets IPC/UPC

Plumbing Code Compliance

IPC & UPC Code Rules for 2" Sanitary Piping

Regulatory parameters, maximum fixture unit capacities, and velocity thresholds.

Minimum Code Slope
1/4" per foot
2.08% Grade (1:48)

Drop Per 10 Feet

2.5 inches

Elev. delta per 10ft stick

Drop Per 50 Feet

12.5 inches

Total fall for 50ft run

Max Drainage Fixture Units

6 DFU

At minimum allowable slope

Min Scouring Velocity

2 ft/sec

Self-cleaning threshold

Governing IPC Reference

Table 704.1

International Plumbing Code

Primary Fixtures Connected to 2" Drains:

Shower drains
Washing machine standpipes
Floor drains
Kitchen sink branch lines with garbage disposal

Trade Installation Advisory: Critical slope requirement for walk-in showers and laundry standpipes to prevent back-siphonage and foam overflows.

Pipe Diameter Navigation

Compare Slope Requirements for Other Pipe Sizes

Explore sanitary fall and grade rules across different drain diameters.

← Smaller Drain 1-1/2" Drain Pipe Slope Master Engine Drain Pipe Slope Calculator Larger Drain → 3" Drain Pipe Slope

Expert FAQ Guide

2" Drain Pipe Slope FAQs

Code questions and fall calculations for 2" sanitary drainage piping.

3 Questions Answered

Q1 What is the required slope for a 2" shower drain?

A 2-inch shower drain pipe must have a minimum fall of 1/4 inch per foot (2.08% pitch). For a 10-foot run, the total drop must be 2-1/2 inches.

Q2 How much drop does a 2" drain need for 20 feet?

Over a 20-foot horizontal run, a 2-inch drain sloped at 1/4" per foot requires a total elevation drop of 5.0 inches (127 mm).

Q3 Can a 2-inch drain pipe have too much slope?

Yes. If a drainage pipe exceeds 1/2" per foot (over 4% grade) without proper vertical transitions, water can outrun solid waste, leaving solids behind in the pipe and leading to repeated blockages.

2" Drain Pipe Fall vs. Run Length Chart

IPC & UPC Code Rules for 2" Sanitary Piping

Primary Fixtures Connected to 2" Drains:

Compare Slope Requirements for Other Pipe Sizes

2" Drain Pipe Slope FAQs

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