Calculate air or fluid flow velocity and volumetric flow from pitot tube differential pressure, head measurements, or traverse readings.

Incompressible-flow estimate. Low pressure differences can be inaccurate; compressible or shock-affected flow needs another model. Flow volume requires a representative average velocity.

Use density at the measurement conditions.

Optional settings

Blank uses 1 (ideal probe); use your calibrated coefficient when known.

Pitot Tube Formula

The following ideal-probe formula is used for steady incompressible flow. The calculator applies a calibrated pitot coefficient C when entered; blank uses C = 1.

V = SQRT (2 × (pt - ps) / d)
  • Where V is the velocity
  • pt is the total pressure
  • ps is the static pressure
  • d is the density

To calculate velocity from a pitot tube, multiply the difference between the total pressure and static pressure by 2, divide by the density of the air, then finally, take the square root of this result.

Pitot Tube Definition

What is a pitot tube?

A pitot tube is a right-angled tube that points into the flow of fluid to measure the pressure. This pressure can then be used to calculate the speed or velocity of the fluid or object moving through the fluid.

These tubes are most often used on aircraft to help determine the speed of the aircraft. GPS measures ground speed; pitot systems measure airspeed relative to the surrounding air. These speeds can differ with wind.

Example Problem

How to calculate velocity from a pitot tube?

The following example outlines the steps and information required to calculate the velocity of fluid from a pitot tube.

First, determine the total pressure reading of the tube. In this example, the total pressure is measured as 50 N/m^2.

Next, determine the static pressure measured by the pitot tube. The static pressure reads 25 N/m^2 for this example.

Next, determine the density of the fluid. In this case, we are looking at room temperature air which has a density of 1.225 kg/m^3.

Finally, calculate the velocity using the formula above:

V = SQRT ( 2*(pt-ps) / d )

V = SQRT ( 2*(50-25) / 1.225 )

V ≈ 6.389 m/s