Calculate volumetric flow based on volume/time or pipe diameter/velocity.
Based on Volume & Time
Based on Pipe Diameter & Velocity
Calculation Results
Cubic Meters per Hour:–
Liters per Minute (L/min):–
Gallons per Minute (US GPM):–
Cubic Meters per Second:–
How to Calculate Volume Flow Rate
The volumetric flow rate (often denoted as Q) is a measure of the volume of fluid that passes through a specific cross-sectional area per unit of time. Understanding how to calculate this metric is crucial for hydraulic engineering, environmental science, HVAC systems, and industrial fluid dynamics.
Method 1: Using Volume and Time
The most fundamental definition of flow rate is simply the amount of fluid collected over a specific period. This method is often used in tank filling or draining scenarios.
Formula: Q = V / t
Where:
Q = Volumetric Flow Rate
V = Volume of fluid (e.g., Liters or Cubic Meters)
t = Time (e.g., Seconds or Minutes)
Example: If a water pump fills a 500-liter tank in 60 seconds, the flow rate is 500 / 60 = 8.33 Liters per second.
Method 2: Using Pipe Diameter and Velocity
In piping systems, it is often more practical to calculate flow rate based on the size of the pipe and the speed at which the fluid is moving. Since pipes are circular, we first calculate the cross-sectional area and then multiply it by the velocity.
Formula: Q = A × v
For a circular pipe, the Area (A) is calculated as π × (Diameter / 2)². Therefore, the expanded formula is:
Q = π × (d/2)² × v
Where:
d = Inner diameter of the pipe
v = Average velocity of the fluid
π = Pi (~3.14159)
Common Unit Conversions
Flow rate can be expressed in many different units depending on the industry. Here are common conversions utilized by this calculator:
1 Cubic Meter per Hour (m³/h) ≈ 16.67 Liters per Minute (L/min)
1 Liter per Minute (L/min) ≈ 0.264 US Gallons per Minute (GPM)
1 Cubic Meter (m³) = 1,000 Liters
Factors Affecting Flow Rate
While the formulas above provide the theoretical flow rate, real-world applications must consider other factors:
Viscosity: Thicker fluids (like oil) resist flow more than water.