Pipe Diameter And Flow Rate Calculator, Online

Pipe diameter calculator

Easily calculate pipe diameter and flow rate using the continuity equation. Our pipe flow calculator helps determine the correct pipe size based on volumetric flow rate and velocity, making it ideal for both liquid and gas flow applications.

Suitable for engineering, HVAC, plumbing, and fluid dynamics.

How Does the Pipe Diameter And Flow Rate Calculator Works?

The calculator applies the continuity equation.

The continuity equation is a fundamental principle in fluid mechanics based on the conservation of mass. It states that for an incompressible fluid (constant density), the mass flow rate remains constant along a streamline. The equation is:

Q = A ⋅ V

Where:

• 𝑄 = Volumetric flow rate (m³/s)
• 𝐴 = Cross-sectional area of the pipe (m²)
• 𝑉 = velocity (m/s)

Since the cross-sectional area of a circular pipe is:

A = π D 2 4

We can rewrite the equation as:

Q = π D 2 4 ⋅ V

Solving for Pipe Diameter (D):

D = 4 ⋅ Q π ⋅ V

where:

• D = internal pipe diameter (m)
• Q = volume flow rate
• V = velocity (m/s)