Drainage Slope Calculator

Drainage Slope Calculator helps you calculate and verify drain pipe slope, drop distance, and run length per IPC minimum slope requirements. Instantly convert between inches per foot, percent, and ratio formats. Verify your drainage installation meets code-required minimum slopes for all pipe sizes, from 2-inch lines to 8-inch and larger horizontal drains. Works 100% offline on the job site for quick slope calculations during installation.

FEATURES
• 3 Calculation Modes: Calculate slope from drop/run, drop from slope/run, or run from slope/drop
• Flexible Unit Conversions: Input and output in inches per foot, percent slope, or ratio (1:X) format
• IPC Minimum Slope Validation: Automatic verification that selected slope meets IPC 2024 requirements
• Pipe Size Support: 11 pipe sizes from 2 inches through 8+ inches with individual minimum slope requirements
• Tiered Slope Standards: 1/4 inch/ft minimum for 2-inch and smaller, 1/8 inch/ft for 3-6 inches, 1/16 inch/ft for 8-inch and larger
• Grade Verification: Checks the slope against the IPC 704.1 minimum for the selected pipe size

HOW IT WORKS
1. Select which value you want to calculate (slope, drop, or run)
2. Enter two known values (e.g., drop and run distance)
3. Select your pipe size (2", 3", 4", 6", 8", etc.)
4. View calculated slope in all three formats (inches/ft, percent, ratio)
5. Instant IPC code compliance verification

PERFECT FOR
• Plumbers and drainage contractors installing drain lines
• Journeyman plumbers and apprentices learning code requirements
• Plumbing inspectors verifying system compliance
• Building contractors and estimators
• Mechanical contractors installing wet vent systems
• Facilities managers maintaining existing drainage systems

OPTIONAL PRO UPGRADE — $2.99 ONE-TIME IN-APP PURCHASE
The following features require a separate one-time in-app purchase. They are not required to use the calculator:
• Unlimited saved calculation history
• PDF export of results
• Dark theme
• Ad-free experience

STANDARDS & COMPLIANCE
IPC 2024 Minimum Drain Slope Requirements (Section 703.2): 1/4 inch per foot for pipes 2 inches and under, 1/8 inch per foot for pipes 3-6 inches, 1/16 inch per foot for pipes 8 inches and larger. UPC (Uniform Plumbing Code) and local plumbing code slope standards. Fully compliant with 2024 International Plumbing Code.

PERFECT FOR
• Professional plumbers and drainage contractors
• Journeyman and apprentice plumbers
• Plumbing inspectors and code officials
• Building contractors and site supervisors
• Mechanical estimators
• Plumbing educators

OFFLINE & PRIVACY
• Works 100% offline - no internet connection required
• No account or registration needed - instant access
• No data collection - all calculations stay on your device
• No tracking or cloud sync

Part of PlumbTools Suite - professional plumbing calculators for code compliance and field calculations. Eliminate sloping errors, speed up installations, and ensure every drainage system meets IPC code requirements with accurate slope calculations.

Recent changes:
Added a link to TradeTools — the one-app version of this calculator and 61 more, for HVAC, electrical, plumbing, fire protection, solar and carpentry. Nothing else changed.