Flow Rate Calculator

How to Calculate Flow Rate

If you’re installing a new filtration system, water softener, or other pipe-based system in your home or business, you will need to know your home’s flow rate to determine the right system size.

Volumetric flow rate, also referred to as volume flow rate, flow rate, or volume velocity, is defined as the volume of fluid passing a point in a given unit of time.[1] The SI unit of flow rate is cubic meters per second (m³/s).

Meaning that a system may be able to handle a given amount or volume of liquid at one time. Knowing what your plumbing flow rate is will enable you to choose a filter or other system type that will work with your plumbing.

Flow rate can be found by simply measuring the amount of fluid that fills a bucket in a given amount of time or using a formula.

Flow Rate Formula

The flow rate of a fluid can be calculated using the volumetric flow rate equation:

Thus, the volume flow rate Q is equal to the cross-sectional area of the pipe A times the velocity of the fluid v.[2]

To use the flow rate formula, substitute the cross-sectional area of the pipe and the velocity of the liquid. For a round pipe, the cross-sectional area can be found using the formula for circle area A = πr².