Flow Rate Calculator
Calculate flow rate, velocity, or cross-sectional area using the continuity equation Q = v × A. Enter any two values to compute the third.
Published by:
isCalculator Editorial Team
Was this calculator helpful?
How to use this tool?
This calculator uses the fundamental flow rate equation: Q = v × A (Flow Rate = Velocity × Cross-sectional Area). It works with metric units (m³/s, m/s, m²).
- Enter any two values into the three input fields (Flow Rate, Velocity, Area). Leave the third field empty.
- Click the Calculate button.
- The missing value is automatically computed and displayed below, along with the formula used.
- All inputs must be positive numbers. Invalid entries show a red error border.
Tip: To start a new calculation, simply clear one field and adjust the other two, then click Calculate again.
Previous Results
| Result | Inputs | Date |
|---|
Frequently Asked Questions
The flow rate is calculated using the continuity equation: Q = v × A, where Q is the volumetric flow rate (m³/s), v is the fluid velocity (m/s), and A is the cross-sectional area (m²).
Enter any two of the three values (flow rate, velocity, or area) and leave the third field empty. Click Calculate and the missing value will be computed and displayed.
The calculator requires exactly two values. If all three fields are filled, an error message will appear asking you to leave one field empty.
Yes, as long as units are consistent. For example, use cm³/s with cm/s and cm². The displayed result uses m³/s, m/s, and m² for the standard SI case.