Industrial Water Services
We have the technology, expertise & experience to serve your advanced water treatment needs. Contact Us Now!

Diameter, Velocity and Flow Rate Calculator

Need to calculate the flow rate of water through a specific pipe diameter? With this diameter, velocity and flow rate calculator, you can determine the exact flow rate or velocity at which water will flow through any given pipe.

This calculator may also be used to determine the appropriate pipe diameter required to achieve a desired velocity and flow rate.

The following formula is used by this calculator to populate the value for the flow rate, pipe diameter or water velocity, whichever is unknown:

V = 0.408 × Q/D2
V = Water Velocity; Q = Flow Rate; D = Pipe Diameter


Flow Rate Calculator

1. Fill in known values for any two fields below.
2. Press the "Calculate" button next to the unknown field.

Flow Rate: gal/min
Pipe Diameter: inches
Water Velocity: ft/s


Flow Rate
Pipe Diameter
Water Velocity