Enter the dynamic pressure (velocity pressure), density, and speed into the calculator to determine the missing variable.

Dynamic Pressure (Velocity Pressure) / Speed Calculator

Enter any 2 values to calculate the missing variable

Dynamic Pressure (Velocity Pressure) Formula

The following formula is used to calculate the dynamic (velocity) pressure, density, or speed when two of the variables are known. Dynamic pressure (q) is commonly used in aerodynamics and is equal to the difference between stagnation pressure and static pressure (q = Pt − Ps) for low-speed flow.

q = 0.5 * ρ * v²

Variables:

  • q is the dynamic pressure (velocity pressure) in pascals (Pa)
  • ρ is the density in kilograms per cubic meter (kg/m³)
  • v is the speed in meters per second (m/s)

To calculate the dynamic pressure, multiply the density by the square of the speed and then multiply the result by 0.5.

What is Dynamic Pressure?

Dynamic pressure (also called velocity pressure) is the pressure associated with a fluid’s motion. In low-speed airflow, it can be interpreted as the difference between stagnation (total) pressure and static pressure measured by a Pitot-static probe. It depends on air density and speed, and it is measured in pascals (Pa). (This is different from atmospheric/static air pressure caused by the weight of the air above you.)

How to Calculate Airspeed from Dynamic Pressure?

The following steps outline how to calculate the airspeed from dynamic pressure.

  1. First, determine the dynamic pressure (q).
  2. Next, determine the air density (ρ).
  3. Next, calculate the speed using the formula v = sqrt(q / (0.5 * ρ)) (equivalently, v = sqrt(2q/ρ)).
  4. If you already know speed and density, you can calculate dynamic pressure using q = 0.5 * ρ * v².
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Dynamic Pressure (q) = 500 Pa

Density (ρ) = 1.225 kg/m³

Speed (v) = √(2q/ρ) = √(2 × 500 / 1.225) ≈ 28.58 m/s