Flow Measurement · Glossary

What is Volumetric Flow Rate?

Symbol: Qm³/h, L/s, GPMFlow Measurement

Volumetric flow rate is the volume of fluid passing a point per unit time, equal to pipe area times average velocity.

Volumetric Flow Rate Explained

Volumetric flow rate tells you how much volume moves through a pipe each second, minute or hour. It is what magnetic, vortex, turbine and ultrasonic meters measure directly.

For gases the volume changes with pressure and temperature, so a volumetric reading at line conditions (actual m³/h) is often converted to standard or normal conditions before it is reported or billed.

Volumetric Flow Rate Formula

Q = A × v

Q	volumetric flow rate (m³/s)
A	internal pipe area = π D² ÷ 4 (m²)
v	average flow velocity (m/s)

Example: A pipe with 100 mm bore has A = 0.007854 m². At 2 m/s, Q = 0.0157 m³/s = 56.5 m³/h.

Calculators for Volumetric Flow Rate

CalculatorPipe Flow Velocity CalculatorFree online calculator with formula and worked example.CalculatorPipe Sizing CalculatorFree online calculator with formula and worked example.CalculatorMass Flow to Volume Flow CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is Volumetric Flow Rate?

Volumetric flow rate is the volume of fluid passing a point per unit time, equal to pipe area times average velocity.

What is the difference between volumetric and mass flow rate?

Volumetric flow is volume per time; mass flow is mass per time. They are linked by density: mass flow = density × volumetric flow.

Which meters measure volumetric flow?

Magnetic, vortex, turbine, ultrasonic and positive displacement meters measure volume. DP meters can give either, depending on how density is handled.