How to Calculate Flow Rate
What is Flow Rate?
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.
Formula
- Q
- Volumetric flow rate (m³/s or L/min)
- A
- Cross-sectional area (m²)
- v
- Fluid velocity (m/s)
- V
- Total volume (m³)
- t
- Time elapsed (s)
Step-by-Step Guide
- 1Q = A × v (m³/s; A in m², v in m/s)
- 2Continuity: A₁v₁ = A₂v₂ (fluid speeds up in narrower sections)
- 31 m³/s = 1,000 L/s = 60,000 L/min
- 4Use consistent units throughout
Worked Examples
Frequently Asked Questions
What is Flow Rate?
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
How accurate is the Flow Rate calculator?
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.
What units does the Flow Rate calculator use?
This calculator works with inches, square metres. You can enter values in the units shown — the calculator handles all conversions internally.
What formula does the Flow Rate calculator use?
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.
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