Mechanical EngineeringP0

Pipe Diameter Calculator

Calculate required pipe diameter from flow rate and target velocity.

Inputs

Enter your values below

Flow Rate*m3/h

Target Velocity*m/s

Typical: 1-3 m/s for liquids

Result

Required Diameter

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Enter values and click Calculate

Formula

√(4 × flow ÷ (π × velocity)) × 1000

Result unit: mm

D = √(4Q / (π × v)). Flow in m³/s, velocity in m/s; ×1000 converts m to mm.

Introduction

Calculate the minimum pipe inner diameter for a given flow rate and design velocity. Essential for hydraulic pipe sizing in process and utility systems.

Calculation Example

For 50 m³/h at 2 m/s target velocity, minimum diameter is 94 mm. Standard DN100 (114.3mm OD, ~102mm ID) would work.

Inputs: flow=50, velocity=2

Result: 93.8 mm

Engineering Applications

•Process pipe sizing
•Hydraulic system design
•Plumbing design
•Pump suction sizing

Frequently Asked Questions

What standard pipe size should I select?

Round up to the nearest standard DN/NPS size. For example, if calc gives 94mm, select DN100 (4-inch).

What velocity should I design for?

Water discharge: 2-3 m/s; suction: <1.5 m/s; compressed air: 6-10 m/s; natural gas: 10-20 m/s.

Related Calculators

Pipe Velocity Calculator Pipe Flow Calculator

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Disclaimer: Calculations are for reference and educational purposes only. Always verify results independently for engineering design. See full disclaimer.