🔵 Free Engineering Tool

Pipe Sizing Calculator

Calculate flow velocity and friction pressure drop for copper, PVC, steel, stainless and polyethylene pipes. Real pipe schedule internal diameters. SI units.

💧 Water / Hydraulic
🔥 Gas

Water Pipe Sizing

Select pipe material, nominal size, and flowrate to calculate velocity and pressure drop.

Selected Pipe

DN25
ID: 27.0 mm | OD: 31.75 mm

Results

Internal Diameter
-mm
Pipe Area
-cm²
Flow Velocity
-m/s
Pressure Drop (per metre)
-Pa/m
Total Pressure Drop
-Pa
Total Pressure Drop (kPa)
-kPa

Recommended Velocity Limits (AS/NZS 3500)

Cold water, general ≤ 3.0 m/s
Hot water, distribution ≤ 2.0 m/s
Sanitary / drainage 0.6 – 3.0 m/s
Friction limit (max) ≤ 400 Pa/m

Gas Pipe Sizing

Size natural gas or LPG reticulation pipes using volumetric flow.

Gas pipe sizing must be verified by a licensed gas fitter. Pressure drop limits: ≤ 0.75 kPa for LP gas, ≤ 1.0 kPa for NG (AS/NZS 5601).

Selected Pipe

DN25
ID: 27.0 mm
Volumetric Flow (m³/h)
-m³/h
Gas Velocity
-m/s
Pressure Drop (Pa/m)
-Pa/m
Total Pressure Drop
-Pa

Need a full hydraulic design?

CCC Engineering delivers complete hydraulic packages, including water, sanitary, stormwater, gas reticulation, and pump systems with full IFC documentation.

Get a Quote Our Hydraulic Services

How to use this calculator

This pipe sizing calculator helps hydraulic engineers, plumbers, and building designers determine the correct pipe diameter for water, gas, and general hydraulic systems. Enter the flow rate and select a pipe material to calculate flow velocity, Reynolds number, friction factor, and pressure drop per metre. The calculator includes pipe data for copper (Type A and Type B), PVC, PE, stainless steel, galvanised steel, and carbon steel across standard Australian pipe sizes.

Calculations use the Darcy-Weisbach equation with the Colebrook-White friction factor, which is the standard method for hydraulic pipe sizing. Material roughness values are built into each pipe type selection. The calculator displays results for all available pipe sizes simultaneously, making it easy to compare options and select the most appropriate diameter for your application.

This tool is intended for preliminary sizing and feasibility assessments. Final pipe sizing for construction documentation must account for fitting losses, available system pressure, temperature effects, and compliance with AS/NZS 3500 for plumbing and drainage. For complex reticulation systems, multi-storey buildings, or fire services, consult a qualified hydraulic engineer.

Related resources