Flow Rate Calculator
Enter the pipe inside diameter and mean velocity to calculate cross-sectional area and volumetric flow in common units.
A QUICK WALKTHROUGH
How to use this tool
- Enter a finite positive inside diameter in meters.
- Enter a finite nonnegative mean velocity in meters per second.
- Calculate the area and volumetric flow rate in m³/s, L/s, L/min, and m³/h.
The calculation
This calculator uses A = πD²/4 for the circular cross-sectional area and Q = vA for volumetric flow rate. Diameter is entered in meters and velocity in meters per second.
Unit conversions
The same result is shown as cubic meters per second, liters per second, liters per minute, and cubic meters per hour.
Defined scope
The result uses only inside diameter and mean velocity. It does not estimate Reynolds number, flow regime, fluid properties, friction, pressure loss, or compressibility.
GOOD TO KNOW
Common questions
What diameter should I enter?
Enter the pipe inside diameter in meters, measured across the flow passage.
What does mean velocity mean?
Use the average fluid velocity across the pipe cross-section, in meters per second.
Does this account for the fluid or pipe roughness?
No. It is a geometric flow-rate calculation and does not use fluid properties, roughness, or pressure information.