Flow Rate Calculator

Flow rate (Q) is the volume of fluid passing a cross-section per unit time. The continuity equation Q = A × v is fundamental to plumbing, HVAC, hydraulics, and engineering

The calculator uses the standard published formula for flow rate. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, square metres. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Q = A × v (m³/s; A in m², v in m/s). Each step in the calculation is shown so you can verify the result manually.