Velocity from Flow Rate Calculator
Liters/min (L/min)
Liters/sec (L/s)
Cubic m/hr (m³/h)
Cubic m/sec (m³/s)
Gallons/min (GPM US)
Cubic ft/min (CFM)
Millimeters (mm)
Centimeters (cm)
Meters (m)
Inches (in)
Feet (ft)
Calculation Results
Cross-Sectional Area:
0.0000 m²
Fluid Velocity (Metric):
0.00 m/s
Fluid Velocity (Imperial):
0.00 ft/s
Formula Used: v = Q / A
How to Calculate Velocity from Flow Rate
Determining fluid velocity from a known volumetric flow rate and pipe diameter is a fundamental calculation in fluid dynamics, plumbing, and HVAC engineering. The relationship helps engineers ensure pipes are sized correctly to prevent excessive noise, erosion, or pressure drops.
The Flow Rate Formula
The basic equation connecting flow rate (Q), velocity (v), and cross-sectional area (A) is:
v = Q / A
Where:
- v = Fluid Velocity (e.g., meters per second, m/s)
- Q = Volumetric Flow Rate (e.g., cubic meters per second, m³/s)
- A = Cross-Sectional Area of the pipe (e.g., square meters, m²)
Calculating Pipe Area
Since most pipes are cylindrical, you first need to calculate the cross-sectional area using the inner diameter (d):
Area (A) = π × (d / 2)² OR A = (π × d²) / 4
Practical Example
Imagine you have water flowing at a rate of 100 Liters per minute through a pipe with an inner diameter of 50 mm.
- Convert Flow Rate: 100 L/min = 0.001667 m³/s.
- Convert Diameter: 50 mm = 0.05 meters.
- Calculate Area: A = π × (0.025)² ≈ 0.001963 m².
- Calculate Velocity: v = 0.001667 / 0.001963 ≈ 0.85 m/s.
Why is Fluid Velocity Important?
Maintaining the correct fluid velocity is critical for system efficiency:
- Too Low: Sediment may settle in the pipes, leading to blockages (especially in wastewater systems).
- Too High: Can cause hydraulic shock (water hammer), pipe erosion, and excessive noise.
Use this Velocity from Flow Rate Calculator to quickly convert between units and ensure your system design meets the required specifications.