Created By : Naaz Fatima

Reviewed By : Phani Ponnapalli

Last Updated : Apr 10, 2023

Flow Rate Calculator is a free tool that finds the flow rate of a fluid provided the diameter and velocity. All you need to do is provide the inputs diameter, velocity in the allotted input section and hit the calculate button to get flow rate quickly.

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Cross-sectional area

What is Flow Rate?

When we talk about flow rate in most of the cases it is volumetric flow rate. Volumetric Flow Rate is defined as the volume of a fluid that passes through a gien cross sectional area per unit of time. Volumetric Flow Rate is denoted by the symbol Q and at times V-V. Volumetric Flow Rate = V/t

One more concept in Flow Rate is Mass Flow Rate or Mass Current. In this case, it is the mass that passes through a given cross sectional area per unit time. Mass Flow Rate is given by = m/t = mass/time.

How to Calculate Flow Rate?

Volumetric Flow Rate: In Order to determine the Volumetric Flow Rate you need to first find out the volume of a portion of a fluid in channel. Volume = A*l where A is the Cross Sectional Area of the Fluid and l is the width of given portion of a fluid. Substituting the Volume in the Flow Rate Formula we get the Volumetric Flow Rate Equation as Volumetric flow rate = V / t = A * l / t


Since l/t is the volume length divided by time we consider it as flow velocity. Thus, Volumetric Flow Rate becomes the equation Volumetric flow rate = A * v. Since majority of the pipes are cylindrical we will have the equation for Volumetric Flow Rate as Volumetric flow rate for cylindrical pipe = π * (d/2)² * v where d is the diameter of the pipe. We can even rearrange this equation to determine the pipe velocity.

Mass Flow Rate: In order to determine the mass rate formula we first need to remind ourselves the density definition i.e. ρ = m / V and rearranging we get m = ρ*V. We know mass flow rate is nothing but the mass of a substance passing per unit time. Mass flow rate = m / t = ρ * V / t = ρ * Volumetric flow rate = ρ * A * v

Thus, Mass Flow Rate = ρ * A * v


Compute the flow rate of a fluid if it is travelling with a velocity of 30 m/s and has a diameter of 0.05m?


Given that

Velocity = 30 m/s

Diameter = 0.05m

We know the formula to calculate Volumetric flow rate = π * (d/2)² * v

Substituting the input parameters we have the equation as under

Volumetric Flow Rate = π * (0.05/2)² * 30 = 0.0589 Cubic Meter Per Second(m³/s)

Physicscalc.Com has got concepts like friction, acceleration due to gravity, water pressure, gravity, and many more along with their relevant calculators all one under one roof.

FAQs on Flow Rate Calculator

1. What is meant by Flow Rate?

Flow Rate is the Quantity of Fluid that flows in a specific period of time.

2. How do I calculate the Flow Rate?

You can calculate the Flow Rate by dividing the capacity of fluid stored(C) with given time.

3. What is Volumetric Flow Rate Formula?

The Formula for Volumetric Flow Rate is Volumetric Flow Rate = V/t

4. What Units are used to measure Flow Rate?

Units used to measure Flow Rate are Cubic Meters Per Second, Cubic Feet Per Second, Gallons Per Minute, etc.

5. What is the Unit of Mass Flow Rate?

Unit of Mass Flow Rate is Kilogram Per Second(Kg/S).