Pitot Tube Calculator

What Is a Pitot Tube?

A Pitot tube is a flow measurement device used to estimate fluid velocity from pressure measurements. It compares the total pressure, also called stagnation pressure, with the static pressure of the flow.

The difference between total pressure and static pressure is the dynamic pressure. Once dynamic pressure and fluid density are known, the velocity can be estimated using Bernoulli's equation.

Pitot Tube Formula

The pressure difference measured by a Pitot-static system is:

For incompressible flow, velocity is calculated as:

where:

• v = fluid velocity (m/s)
• ΔP = dynamic pressure (Pa)
• P_total = total or stagnation pressure (Pa)
• P_static = static pressure (Pa)
• ρ = fluid density (kg/m³)

Volumetric Flow Rate

If the cross-sectional flow area is known, the volumetric flow rate can be estimated with:

where Q is volumetric flow rate in m³/s and A is the duct or pipe area in m².

How to Use the Pitot Tube Calculator

1. Enter the measured total pressure in pascals.
2. Enter the measured static pressure in pascals.
3. Enter the fluid density in kg/m³.
4. Optionally enter the flow area if you want volumetric flow rate.
5. Click calculate to get dynamic pressure, velocity, optional flow rate, and step-by-step results.

Example Pitot Tube Calculation

Suppose a Pitot tube measures:

• Total pressure: 1200 Pa
• Static pressure: 1000 Pa
• Air density: 1.2 kg/m³
• Duct area: 0.05 m²

First, calculate dynamic pressure:

Then calculate velocity:

If the duct area is 0.05 m², the flow rate is:

Important Assumptions

• The flow is treated as incompressible.
• The Pitot tube is aligned with the flow direction.
• Total and static pressures use the same reference pressure.
• Density is known and approximately constant.
• Viscous losses and probe calibration corrections are neglected.

Where Pitot Tubes Are Used

• Aviation airspeed measurement
• Wind tunnel testing
• HVAC duct velocity measurement
• Industrial ventilation systems
• Pipeline and channel flow testing
• Fluid mechanics laboratories

Frequently Asked Questions

What is the purpose of a Pitot tube?

A Pitot tube measures fluid velocity by comparing total pressure and static pressure. The pressure difference gives dynamic pressure, which can be converted into velocity.

What is dynamic pressure?

Dynamic pressure is the pressure associated with the motion of the fluid. In a Pitot-static measurement, it is calculated as total pressure minus static pressure.

Can a Pitot tube be used for liquids?

Yes. Pitot tubes can be used for liquids and gases, provided the density is known and the measurement ports are not clogged or disturbed.

Does air density affect the result?

Yes. Velocity is inversely related to the square root of density. If density changes because of temperature, altitude, or humidity, the calculated velocity also changes.

Why must total pressure be greater than static pressure?

In normal Pitot tube operation, total pressure is greater than static pressure because it includes the dynamic pressure of the moving fluid. If total pressure is lower, the inputs are likely reversed or inconsistent.

Is this suitable for aircraft airspeed?

It is suitable for basic educational calculations. Real aircraft airspeed systems may require compressible-flow equations, calibration corrections, altitude corrections, and instrument corrections.

References

• Munson, Young, Okiishi — Fundamentals of Fluid Mechanics
• White — Fluid Mechanics
• Fox & McDonald — Introduction to Fluid Mechanics
• Abbott — Principles of Aerodynamics