Prandtl probe calculator

flow velocity calculator

online since 2001

Additional features in download version

save/open results
print results
custom fluid properties
K factor for fittings, resistance coefficient
compressible isothermal flow

Registration and subscription

Please login for full calculator service. Use the form on the top of the page.
Register an account if you don't have one.
Active subscription is required for full services.

Need a helping hand?

If you need a quick calculation, but you are not still familiar how to use the calculator, you can order calculation service from the calculator developer.
Calculation setup
Fluid properties
Flow rates and velocity
Flow is subsonic
Pipe dimensions

Calculator description

Read more about calculator application and check if calculator is suitable for your problem.

Also, read about calculation procedures, what you have to know for the calculations and what limitations apply.

Registration and subscription

Subscribed users have access to the full service which includes:

  • One click switch from metric to imperial units
  • Export results in word or excel format
  • Preview, copy and paste results from a web page to your text editor
  • Send results to you email


Calculator start selection

Read all about available deployments. In any way of utilizing calculator, Internet connection is required, for authentication at least.

Issues and answers

Having problems with calculators usage? Read more about known issues and problems and way to solve it.

issues and answers


pt - total (stagnation) pressure
Measured pressure of the stream when flow velocity is brought to zero isentropically, in the center of the Prandtl probe
pd - dynamic pressure
Differential pressure calculated as the difference between the total (stagnation) and the static pressure.
p - static pressure
Measured pressure of the flow without the affect of the fluid movement (kinetic) energy
ρ - fluid density
Mass per unit of volume
R - gas constant
Gas constant in terms of energy per unit of mass and temperature, for gas density calculation using ideal gas state equation
κ - isentropic coefficient
Specific heat ratio
T - temperature
Fluid temperature for gas density calculation based on the ideal gas state equation
q - volumetric flow rate
Fluid flow rate in terms of units of volume per unit of time
ṁ - mass flow rate
Fluid flow rate in terms of units of mass per unit of time
V - velocity
Flow velocity in terms of units of distance per unit of time
c - speed of sound
Sound speed for given gas and actual conditions in terms of pressure, density and temperature
M - Mach number
Flow velocity and actual speed of the sound ratio
D - internal diameter
Internal circular pipe diameter
A - area
Internal pipe cross section area
h - channel height
Height of the channel for rectangled closed pipe line
w - channel width
Width of the channel for rectangled closed pipe line

Calculation setup

Select value to input. You should enter selected one. The other one will be calculated.
total (stagnation) pressure
dynamic pressure
Select value to input. You should enter selected one. The other one will be calculated.
fluid density
Select pipe shape
round pipe
full cross section fluid flow
rectangle pipe
for rectangle channels and full cross section flow

Related calculators available for download