Calculadora de Tubulação Hidráulica
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Q = π·r²·v (r = d/2000 m)
About this calculator
The Hydraulic Pipe Calculator determines the maximum flow rate in a pipe based on the internal diameter and fluid velocity. The flow rate is calculated using the formula Q = π·r²·v, where r is the internal radius in meters (obtained from the diameter in millimeters divided by 2000) and v is the fluid velocity in meters per second. The result is provided in liters per second, facilitating the sizing of hydraulic systems.
This tool is useful for engineers, technicians, and construction professionals who need to size pipes for water supply, irrigation systems, sewage networks, or building installations. Knowing the required flow and recommended velocity (typically 0.5 to 2 m/s for water), you can choose the appropriate pipe diameter, avoiding undersizing that causes pressure loss or oversizing that increases costs.
When using the calculator, enter the pipe's internal diameter in millimeters and the fluid velocity in meters per second. Remember that the maximum recommended velocity for water in metal pipes is 3 m/s and for PVC, 2 m/s, to avoid noise and erosion. The calculator assumes uniform flow and does not consider friction losses, bends, or fittings, providing a theoretical ideal estimate.
Caution: Ensure you use the actual internal diameter, not the nominal one. Pipes of different materials (PVC, copper, steel) may have different wall thicknesses, altering the internal diameter. For systems with many fittings, consult a hydraulic engineer for more accurate calculations.
Frequently asked questions
What is the recommended velocity for water in pipes?
For water, the recommended velocity is between 0.5 and 2 m/s. In metal pipes, it can reach 3 m/s, while in PVC the maximum is 2 m/s to avoid noise and wear.
How do I convert nominal diameter to internal diameter?
Nominal diameter is a commercial reference. Check the manufacturer's table for the actual internal diameter, which depends on the pipe wall thickness.
Does this calculator consider pressure loss?
No. The calculation is for theoretical maximum flow, without considering friction losses, bends, or fittings. For real sizing, use the Darcy-Weisbach equation.
Can I use this calculator for gases?
The formula is valid for incompressible fluids. For gases, compressibility must be considered, so it is not recommended without adjustments.
What if the calculated flow rate is too low?
Increase the pipe diameter or the fluid velocity, respecting the maximum velocity limits to avoid damage and noise.