Dynamic Pressure Calculator Formula
Understand the math behind the dynamic pressure calculator. Each variable explained with a worked example.
Formulas Used
Dynamic Pressure (q)
q = 0.5 * density * pow(velocity, 2)Dynamic Pressure
q_kpa = 0.5 * density * pow(velocity, 2) / 1000Variables
| Variable | Description | Default |
|---|---|---|
density | Fluid Density (rho)(kg/m³) | 1.225 |
velocity | Velocity (V)(m/s) | 100 |
How It Works
Dynamic Pressure
Dynamic pressure represents the kinetic energy per unit volume of a flowing fluid. It is the key scaling parameter for aerodynamic forces.
Formula
q = 0.5 × rho × V²
where rho is the fluid density and V is the freestream velocity. All aerodynamic forces (lift, drag) are proportional to dynamic pressure, which is why it appears in every force coefficient definition.
Worked Example
Air at sea-level standard density flowing at 100 m/s.
- 01q = 0.5 × 1.225 × 100²
- 02q = 0.5 × 1.225 × 10000
- 03q = 6125 Pa = 6.125 kPa
Frequently Asked Questions
What is the difference between dynamic and static pressure?
Static pressure is the ambient pressure of the fluid at rest. Dynamic pressure is the additional pressure due to fluid motion. Total (stagnation) pressure equals static plus dynamic pressure in incompressible flow.
Does dynamic pressure apply to water as well?
Yes. The formula q = 0.5 × rho × V² applies to any fluid. Since water density is about 800 times that of air, the dynamic pressures are much higher for the same speed.
Why does dynamic pressure matter for aircraft design?
All aerodynamic loads on an aircraft scale with dynamic pressure. Structural designers must ensure the airframe can withstand forces at the maximum dynamic pressure (called q-max or Vd conditions).
Ready to run the numbers?
Open Dynamic Pressure Calculator