Pressure Drop Calculator

“In this Pressure Drop Calculator, we will show you how to find the pressure drop in a pipe in just a few seconds.

We will also help you understand what pressure drop is, why it happens in fluid flow, and how to calculate it using the Darcy-Weisbach formula.

What is pressure drop? How does pipe length, diameter, or flow rate affect it? How to calculate it step by step? Find all the answers here!”

💨 Pressure Drop Calculator

Darcy Friction Factor (f):

Pipe Length (L, meters):

Pipe Diameter (D, meters):

Fluid Density (ρ, kg/m³):

Volumetric Flow Rate (Q, m³/s):

📘 Detailed Formula Explanation

The pressure drop in a pipe is calculated using the Darcy-Weisbach equation:

ΔP = f × (L/D) × (ρ × v² / 2)

Where:

ΔP = Pressure drop (Pa)
f = Darcy friction factor (dimensionless)
L = Pipe length (m)
D = Pipe diameter (m)
ρ = Fluid density (kg/m³)
v = Fluid velocity (m/s), calculated as v = 4Q / (π D²)
Q = Volumetric flow rate (m³/s)

Stepwise Problem Example

Problem: Water flows through a 50-meter long pipe of diameter 0.05 m at a volumetric flow rate of 0.002 m³/s. The fluid density is 1000 kg/m³ and the Darcy friction factor is 0.02. Calculate the pressure drop in the pipe.

Step 1: Calculate the fluid velocity using the formula:

v = 4Q / (π D²)

Substitute the values: v = 4 × 0.002 / (π × 0.05²) ≈ 1.018 m/s

Step 2: Calculate the pressure drop using Darcy-Weisbach equation:

ΔP = f × (L/D) × (ρ × v² / 2)

Substitute the values: ΔP = 0.02 × (50 / 0.05) × (1000 × 1.018² / 2) ≈ 10353 Pa

Step 3: Convert units (optional):
ΔP ≈ 10.353 kPa ≈ 1.502 psi

Answer: The pressure drop ΔP ≈ 10.35 kPa (or 1.5 psi).

📋 Pressure Drop Reference Table

Parameter	Typical Values	Units	Notes
Darcy Friction Factor (f)	0.008 – 0.04	–	Depends on pipe material & flow regime
Pipe Diameter (D)	0.01, 0.025, 0.05, 0.1, 0.2	m	Internal diameter of standard pipes
Pipe Length (L)	10 – 100	m	Common lengths for water/gas pipelines
Fluid Density (ρ)	800 – 1200	kg/m³	Water: 1000, Light oils: 800–900
Volumetric Flow Rate (Q)	0.0005 – 0.01	m³/s	Small to medium-scale pipe systems
Velocity (v)	0.5 – 3	m/s	Safe flow velocities to avoid erosion

FAQs

What is pressure drop?

Pressure drop is the reduction in fluid pressure as it flows through a pipe due to friction.

What causes pressure drop in pipes?

Friction between the fluid and pipe walls slows the flow, causing pressure to drop.

Why is knowing pressure drop important?

It helps design pipes correctly, ensures efficient flow, and prevents damage to pumps or pipelines.

Can I get the pressure drop in different units?

Yes! Our calculator shows it in Pa, kPa, and psi instantly.