Volumetric Flow Rate Calculator

Determine the volumetric flow rate of a fluid with our simple and accurate calculator.

The volumetric flow rate is a measure of the amount of fluid that passes through a given section per unit of time. The formula used to calculate the volumetric flow rate is:

Q = A * v

  • Q: Volumetric flow rate (in m3/s)
  • A: Cross-sectional area of the flow (in m2)
  • v: Fluid velocity (in m/s)

Practical Examples

Here are some concrete applications:

  1. Garden Hose: If a garden hose has a cross-sectional area of 0.005 m2 and the water flows at a speed of 1 m/s, the flow rate is

    Q = 0.005 * 1 = 0.005 m3/s.

  2. River: For a river section of 10 m2 with a flow speed of 2 m/s, the flow rate is Q = 10 * 2 = 20 m3/s.


The calculation of the volumetric flow rate is essential in many fields, such as:

  • Hydraulic engineering and irrigation system design
  • Environmental studies and water resource management
  • Design and analysis of plumbing and heating systems

Calculation of Cross-Sectional Area

The cross-sectional area is a key element in determining the volumetric flow rate. It varies depending on the shape of the section through which the fluid flows. Here is how to calculate it for different shapes:

Circular Section

For a circular section (like a round pipe):

A = pi * r^2

  • A: Area of the section (in m2)
  • r: Radius of the circular section (in m)

Rectangular Section

For a rectangular section (like a channel):

A = l * w

  • A: Area of the section (in m2)
  • l: Length of the section (in m)
  • w: Width of the section (in m)

Other Common Shapes

For other shapes, like elliptical or triangular sections, the formulas become more complex. For example:

  • Elliptical Section: A = pi * a * b (where a and b are the semi-axes)
  • Triangular Section: A = (base * height) / 2

To calculate these areas, you can use our calculators found here: plane geometry calculators.


What is the importance of knowing the volumetric flow rate in plumbing systems?
Knowing the flow rate allows for proper sizing of pipes and pumps, thus ensuring efficient operation of the system.
Is the volumetric flow rate always constant in a pipe?
No, it can vary depending on pressure, temperature, and other factors affecting the fluid velocity and cross-sectional area.

See also

Fluid Mechanics
Unit Converter