Pipe Diameter & Flow Rate Calculator

Professional tool for calculating pipe dimensions, flow velocity, and volumetric flow rate using continuity equation (Q = A × V)

Pipe Inner Diameter Calculator

Enter Outer Diameter (mm)

Enter Wall Thickness (mm)

Find Pipe Diameter from Flow Rate & Velocity

📊 Flow Rate (Q)

m³/s

⚡ Flow Velocity (V)

m/s

Calculate Flow Rate from Pipe Diameter & Velocity

📏 Pipe Diameter (D)

⚡ Flow Velocity (V)

m/s

Calculate Velocity from Flow Rate & Pipe Diameter

📊 Flow Rate (Q)

m³/s

📏 Pipe Diameter (D)

📈 Pipeline Pressure Drop Profile

Pipe Length (km)

Number of Bends

Elevation Change (m)

🏋️ Pipe Strength & Wall Thickness Calculator

Internal Pressure (bar)

Pipe OD (mm)

Material Yield Strength (MPa)

📏

Required Wall Thickness

💥

Burst Pressure

bar

⚖️

Safety Factor

(min 3.5)

🎯 Smart Pipe Selection Wizard

Answer few questions and we'll recommend the best pipe!

⚖️ Pipe Weight & Load Calculator

Pipe Material

OD (mm)

Wall Thickness (mm)

Length (m)

⚖️

Pipe Weight

💧

Water Weight (full)

🏗️

Total Load

📉 Darcy-Weisbach Friction Loss Calculator ?

Pipe Length (L)

Pipe Diameter (D)

Flow Velocity (V)

m/s

Roughness (ε)

🌡️ Thermal Expansion Calculator ?

Pipe Length (L)

Temperature Change (ΔT)

°C

Pipe Material

🔄 Professional Unit Converter

Flow Rate

m³/s: 0

L/s: 0

L/min: 0

GPM: 0

m³/hr: 0

Pressure

bar: 0

psi: 0

kPa: 0

MPa: 0

kg/cm²: 0

🎨 Pipe Color Coding (Industrial Standards)

💧 Water - Blue

🔥 Fire - Red

⚠️ Gas - Yellow

💨 Air - Green

⚗️ Steam - Silver

🧪 Chemicals - Purple

🧪 Common Fluid Properties at 20°C

Fluid	Density (kg/m³)	Viscosity (cP)	Applications
Water	998	1.00	General purpose
Diesel	832	3.20	Fuel lines
Crude Oil	870	10–100	Pipeline transport
Milk	1030	2.10	Food industry
Air (gas)	1.2	0.018	Pneumatic systems
Steam (100°C)	0.6	0.012	Heating systems

📊 Pipe Schedule & Pressure Ratings (Steel Pipe - ASTM A53) ?

Nominal Size (inches)	Schedule	Wall Thickness (mm)	Working Pressure (psi)	Common Applications
1/2" (15mm)	40	2.77	2900	General plumbing
1/2" (15mm)	80	3.73	4200	High pressure
3/4" (20mm)	40	2.87	2300	General plumbing
3/4" (20mm)	80	3.91	3400	High pressure
1" (25mm)	40	3.38	2100	General plumbing
1" (25mm)	80	4.55	3100	High pressure
2" (50mm)	40	3.91	1300	Water mains
2" (50mm)	80	5.54	2000	Industrial
4" (100mm)	40	6.02	900	Water mains
4" (100mm)	80	8.56	1400	Industrial

📊 Standard Pipe Sizes (Schedule 40) ?

Continuity Equation: Q = A × V where A = π × (D²/4)

📌 Quick Tips

• Optimal velocity for water: 1-3 m/s
• Minimum velocity to prevent settling: 0.6 m/s
• Maximum velocity to prevent erosion: 5 m/s
• Recommended velocity for steam: 20-40 m/s
• Recommended velocity for air: 10-30 m/s

⚡ Common Applications

• Water supply systems
• HVAC piping
• Industrial process piping
• Drainage systems
• Fire sprinkler systems
• Natural gas distribution

📐 Units Conversion

• 1 m³/s = 1000 L/s = 15850 GPM
• 1 m = 1000 mm = 3.28 ft
• 1 m/s = 3.6 km/h = 2.24 mph
• 1 psi = 6.895 kPa
• 1 bar = 14.5 psi

🔧 Common Pipe Materials & Properties ?

⚙️

Steel Pipe

Pressure: High (up to 4000 psi)

Max Temp: 800°F (427°C)

Roughness: 0.046 mm

Applications: High pressure, steam, gas

🧪

PVC Pipe

Pressure: Low-Medium (up to 450 psi)

Max Temp: 140°F (60°C)

Roughness: 0.0015 mm

Applications: Water supply, drainage, irrigation

🔄

Copper Pipe

Pressure: Medium (up to 1000 psi)

Max Temp: 400°F (204°C)

Roughness: 0.0015 mm

Applications: Plumbing, HVAC, refrigeration

🏭

HDPE Pipe

Pressure: Medium (up to 300 psi)

Max Temp: 140°F (60°C)

Roughness: 0.0015 mm

Applications: Water mains, gas distribution

❓ Frequently Asked Questions

What is the difference between ID and OD? ▼

ID (Inner Diameter) is the internal diameter of the pipe through which fluid flows. OD (Outer Diameter) is the external diameter including the pipe wall. The relationship is: ID = OD - 2 × wall thickness. For flow calculations, always use the Inner Diameter.

What is Pipe Schedule? ▼

Pipe Schedule indicates the wall thickness of the pipe. Higher schedule numbers mean thicker walls and higher pressure ratings. Common schedules include: Schedule 40 (standard), Schedule 80 (thicker), and Schedule 160 (extra thick). The same nominal pipe size with different schedules will have the same OD but different IDs.

How do I select the right pipe size? ▼

Pipe size selection depends on: flow rate requirements, allowable pressure drop, fluid velocity limits, available pressure, and future expansion needs. Generally, select a pipe size that keeps velocity between 0.6-3 m/s for liquids and 10-30 m/s for gases. Consider both initial cost (smaller pipes are cheaper) and operating cost (larger pipes reduce pumping costs).

What is Reynolds Number and why is it important? ▼

Reynolds Number (Re) determines whether flow is laminar (Re < 2000), transitional (2000-4000), or turbulent (Re > 4000). It affects friction factor calculations and heat transfer characteristics. For water at typical velocities in pipes, flow is usually turbulent (Re > 4000).

What is the difference between flow rate and velocity? ▼

Flow Rate (Q) is the volume of fluid passing through a pipe per unit time (m³/s or L/s). Velocity (V) is the speed of fluid movement (m/s). They are related by: Q = A × V, where A is the cross-sectional area. For the same flow rate, a smaller pipe results in higher velocity.