Fluid Flow Calculator

Volumetric flow rate from pipe diameter and velocity — Q = A · v.

Calculator Science & Engineering Updated Apr 19, 2026
How to Use
  1. Enter pipe inner diameter and fluid velocity.
  2. Flow rate, Reynolds number, and regime appear.
Pipe + fluid
Presets
Flow

Show Work

Enter values to see the step-by-step calculation.

Formulas

Area
A = π · (d/2)²
Flow rate
Q = A · v
Reynolds
Re = v · d / ν
Regime
< 2 300 laminar · > 4 000 turbulent

About the Fluid Flow Calculator

Use the Fluid Flow Calculator — a free, easy tool for science and engineering work. Nothing is uploaded, and you do not need an account. Volumetric flow rate from pipe diameter and velocity — Q = A · v.

How it works

Put each value in its box and read the answer as you go. Because it recalculates live, you can play with the inputs to see how each one moves the result — handy for checking your own working or planning ahead. Everything happens on your device, so it is fast and private.

Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.

Frequently Asked Questions

How do I use the Fluid Flow Calculator?

Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.

Do I need to install or sign up for anything?

Not at all — it runs in the browser with nothing to install and no account. After it loads once, it even works without an internet connection.

Is my information private?

Yes. Everything happens in your browser. Nothing you type is sent to a server or saved anywhere.

Common Use Cases

Check your work

Worked it out yourself? Use the Fluid Flow Calculator to make sure your answer is right.

Learn while you do it

Seeing what you put in and what comes out helps you understand how they fit together.

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Type what you have and get the answer in seconds — on a phone, tablet, or computer.

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