Drainage Pipe Calculator
Size drainage pipes based on fixture units (DFU) and gradient requirements. Calculate branch, stack, and vent pipe diameters for residential and commercial plumbing systems.
DFU = Drainage Fixture Units (measure of probable discharge)
Simultaneity factor: 0.5 (reduces peak load)
Calculate vertical stack for multi-floor buildings
Add fixtures and click Calculate to size drainage pipes
Notes:
- Calculations based on BS EN 12056-2 for gravity drainage
- DFU (Drainage Fixture Units) represent probable discharge
- Simultaneity factors account for non-simultaneous usage
- Stack sizing considers total load from all floors
- Consult local codes for specific requirements
DISCLAIMER
This calculator provides ESTIMATES for preliminary planning purposes. Results are based on standard assumptions and may not reflect your specific project conditions.
By using this tool, you acknowledge that:
1. All calculations are approximate and based on typical industry standards and assumptions.
About This Calculator
The Drainage Pipe Calculator helps plumbing engineers and MEP contractors size sanitary drainage systems based on fixture units (DFU) and gradient requirements. Calculate branch, stack, and vent pipe diameters for residential and commercial plumbing systems across the UAE and Gulf. Follows international plumbing codes including UPC and IPC with adaptations for local building regulations.
When to Use This Calculator
- Sizing horizontal branch drains for bathroom groups
- Calculating soil stack diameters for multi-story buildings
- Determining vent pipe sizes for proper system function
- Verifying gradient requirements for horizontal pipes
- Preparing drainage BOQs and tender specifications
How to Use This Calculator
List Fixtures
Select fixture types (WC, lavatory, shower, floor drain) and quantities connected to the branch.
Calculate Total DFU
The calculator sums drainage fixture units based on fixture type (WC = 4 DFU, lavatory = 1 DFU, etc.).
Select Pipe Type
Choose from uPVC, cast iron, or HDPE - affects minimum diameter recommendations.
Set Gradient
Enter pipe gradient (typically 1:40 to 1:80 for horizontal drains) to determine flow capacity.
Review Sizes
Get recommended pipe diameters for branches, stacks, and vents with velocity check.
Typical Scenarios in UAE & Gulf Projects
MEP contractor sizes drainage for a 40-floor tower with 4 apartments per floor. Each apartment has 10 DFU. The calculator determines 100mm branch drains, 150mm main stack, and 100mm vent stack, accounting for simultaneous usage factors and pipe material (uPVC).
Plumbing engineer designs drainage for public restrooms with 20 WCs and 15 lavatories (total 95 DFU). Calculator recommends 150mm main drain at 1:60 gradient, 200mm connection to municipal sewer, meeting ADDC standards.
Frequently Asked Questions
Take Your Calculations Further
This calculator reflects the logic built into Arkan's construction management platform.
Last Updated: January 2026
Standards Reference: Uniform Plumbing Code (UPC), International Plumbing Code (IPC), DEWA/ADDC Drainage Regulations