Flow Rate Calculator
Calculate volumetric and mass flow rates for fluids in pipes, channels, and vessels
Flow Rate Calculator
Internal diameter of the pipe
Average flow velocity
Water: 998 kg/m³ at 20°C, Air: 1.225 kg/m³ at 15°C
Area in square meters (m²)
Flow Rate Results
Formulas: Q = A × v (volumetric), ṁ = ρ × Q (mass)
Cross-sectional area: 0.000000 m²
Flow velocity: 0.000 m/s
Fluid density: 998.0 kg/m³
Example Calculation
Water Flow in Garden Hose
Pipe: Garden hose with 1/2 inch (12.7 mm) diameter
Velocity: 2 m/s water flow
Density: 998 kg/m³ (water at 20°C)
Calculation
Area = π × (0.0127/2)² = 0.0001267 m²
Q = 0.0001267 m² × 2 m/s = 0.0002534 m³/s
Q = 0.254 L/s = 15.2 L/min = 4.0 gal/min
Mass flow rate: 998 × 0.0002534 = 0.253 kg/s
Common Fluid Densities
Typical Flow Velocities
Water Systems
- • Gravity flow: 0.5-1.5 m/s
- • Distribution: 1-3 m/s
- • Pumped systems: 2-4 m/s
Gas Systems
- • Natural gas: 10-20 m/s
- • Air ducts: 3-15 m/s
- • Steam lines: 20-40 m/s
Flow Rate Tips
Higher velocities increase pressure losses
Continuity equation: mass in = mass out
Reynolds number determines flow type
Consider temperature effects on density
Understanding Flow Rate
What is Flow Rate?
Flow rate is the quantity of fluid that passes through a given cross-sectional area per unit of time. There are two main types: volumetric flow rate (volume per time) and mass flow rate (mass per time). Understanding flow rate is crucial for designing piping systems, pumps, and flow measurement devices.
Applications
- •Water supply and distribution systems
- •HVAC and ventilation design
- •Chemical processing and reactors
- •Pump and fan sizing
Key Relationships
Flow rate calculations are based on the continuity equation, which states that mass cannot be created or destroyed in a steady flow system. This leads to the fundamental relationship between flow rate, cross-sectional area, and velocity.
Flow Types
- •Laminar: Re < 2300 (smooth, layered flow)
- •Transitional: 2300 < Re < 4000
- •Turbulent: Re > 4000 (chaotic, mixed flow)
Essential Formulas
Volumetric Flow Rate
Q = A × v
Where A is cross-sectional area and v is velocity
Mass Flow Rate
ṁ = ρ × Q = ρ × A × v
Where ρ is fluid density
Circular Pipe Area
A = π × (d/2)²
Where d is the pipe diameter
Reynolds Number
Re = ρ × v × d / μ
Where μ is dynamic viscosity