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Physics

Froude Number Calculator

Compare inertial flow speed with the gravity-wave scale.

SI units shown beside each fieldIdeal model explained below
Physics lab
Physics lab

Use the units beside each input and review the model assumptions.

See the method

Define your system

Runs on your device

Your calculated quantity

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter mean speed, characteristic length, gravity.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Froude number Fr = v/sqrt(gL).

A WORKED EXAMPLE

Using mean speed = 2 m/s, characteristic length = 1 m, gravity = 9.80665 m/s², the result is 0.638659914. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

For open-channel flow use hydraulic depth as the characteristic length. Other geometries can require a different length convention.

What to keep in mind

For open-channel flow use hydraulic depth as the characteristic length. Other geometries can require a different length convention. An idealized educational model using the stated SI units. Real systems may need additional forces, losses or experimental measurements. Not a safety or equipment specification.

Common questions

How do I use this froude number calculator?

Compare inertial flow speed with the gravity-wave scale. Enter mean speed in m/s, characteristic length in m, gravity in m/s². The starting example is editable; use values for the same system or project.

Which assumptions affect this result?

For open-channel flow use hydraulic depth as the characteristic length. Other geometries can require a different length convention.

Methodology maintained by ClarityKit. How these tools are built and checked.