Last Updated: October 20, 2025
Calculate pipe flow, pressure drop, and velocity using the Darcy-Weisbach equation instantly with our advanced hydraulic engineering calculator supporting multiple units and comprehensive flow analysis for pipe sizing, pump selection, and fluid system design applications.
Enter pipe dimensions, fluid properties, and flow conditions below to calculate pressure drop and velocity instantly.
Use the input fields to specify pipe diameter, length, fluid properties, and flow rate for accurate calculations.
Enter values to see results
The Pipe Flow Calculator is a comprehensive hydraulic engineering tool that calculates pressure drop, velocity, and flow characteristics in pipes using the Darcy-Weisbach equation. This calculator is essential for pipe sizing, pump selection, and fluid system design. It provides detailed analysis including Reynolds number, friction factor, and pressure drop calculations for various pipe materials and fluid conditions.
For more information about pipe flow and fluid mechanics, visit Wikipedia: Pipe Flow and Wikipedia: Fluid Mechanics.
In hydraulic engineering and fluid mechanics, pipe flow analysis is crucial for designing water distribution systems, HVAC systems, industrial piping, and pump systems. This calculator helps engineers and technicians determine pressure losses, select appropriate pipe sizes, and optimize fluid system performance. It's also essential for understanding fluid behavior, energy losses, and system efficiency in pipes and conduits.
Pipe flow analysis is fundamental to hydraulic engineering - it determines pressure losses and system performance in fluid transport.
Whether you're designing water supply systems, sizing pumps, calculating pressure drops, or analyzing fluid dynamics, this calculator provides accurate, instant results with comprehensive hydraulic analysis for all your engineering calculations. For related calculations, explore our photon energy calculator, volumetric flow rate calculator, velocity calculator, projectile motion calculator, and terminal velocity calculator.
ΔP = f × (L/D) × (ρv²/2)
Where ΔP = pressure drop, f = friction factor, L = pipe length, D = diameter, ρ = density, v = velocity
The Darcy-Weisbach equation is the fundamental equation for calculating pressure drop due to friction in pipes. The friction factor (f) depends on the Reynolds number and relative roughness. For laminar flow (Re < 2,300), f = 64/Re. For turbulent flow, the Colebrook-White equation is used to determine the friction factor.
The Reynolds number (Re = ρvD/μ) determines the flow regime and affects the friction factor calculation. Laminar flow occurs at Re < 2,300, transitional flow at 2,300 < Re < 4,000, and turbulent flow at Re > 4,000. The relative roughness (ε/D) also significantly affects friction factor in turbulent flow.
Reynolds Number: Re = ρvD/μ (determines flow regime)
Friction Factor (Laminar): f = 64/Re (Re < 2,300)
Friction Factor (Turbulent): Colebrook-White equation
Velocity: v = Q/A = 4Q/(πD²)
Pressure Drop: ΔP = f(L/D)(ρv²/2)
Pipe roughness values vary significantly with material: smooth pipes (ε = 0.0015 mm), steel pipes (ε = 0.045 mm), cast iron (ε = 0.26 mm), and concrete (ε = 0.3-3.0 mm). The relative roughness (ε/D) is crucial for friction factor determination in turbulent flow conditions.
Given:
Step 1: Calculate velocity
v = Q/A = 4Q/(πD²)
v = 4 × 0.02 m³/s / (π × 0.1² m²)
v = 2.55 m/s
Step 2: Calculate Reynolds number
Re = ρvD/μ = 1000 × 2.55 × 0.1 / 0.001
Re = 255,000 (turbulent flow)
Step 3: Calculate friction factor
Using Colebrook-White equation: f ≈ 0.019
Step 4: Calculate pressure drop
ΔP = f(L/D)(ρv²/2)
ΔP = 0.019 × (500/0.1) × (1000 × 2.55²/2)
ΔP = 308,000 Pa = 308 kPa
Final Answer
308 kPa
Pressure drop in 500m steel pipe
💡 Did you know? The Darcy-Weisbach equation is more accurate than the Hazen-Williams equation for most engineering applications and works for all fluid types and pipe materials!
| Field/Application | Typical Flow Rate Range | Importance |
|---|---|---|
| Water Distribution | 0.1-100 L/s | Critical for municipal water supply systems |
| HVAC Systems | 0.01-10 L/s | Essential for heating and cooling systems |
| Industrial Processing | 1-1000 L/s | Important for manufacturing and chemical processes |
| Oil and Gas | 10-10000 L/s | Critical for pipeline transportation |
| Wastewater Treatment | 0.1-100 L/s | Essential for environmental protection |
| Fire Protection | 1-100 L/s | Critical for safety and emergency systems |
| Agricultural Irrigation | 0.1-50 L/s | Important for crop production and water management |
| Power Generation | 10-1000 L/s | Essential for cooling and steam systems |
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