Enter the total lift force, air density, coefficient of lift, and wing surface area into the calculator to determine the stall speed of an aircraft.

Stall Speed Formula

The following formula is used to calculate a stall speed.

V = SQRT ( 2*L / (Cl * p * S ) 
  • Where V is the stall speed
  • L is the lift force
  • Cl is the coefficient of lift
  • p is the air density
  • S is the surface area of the wings

To calculate the stall speed, multiply the lift force by 2, divide by the product of the lift coefficient, air density, and surface area, then take the square root of this result.

Stall Speed Definition

What does stall speed mean? A stall speed is defined as the velocity of an aircraft in which the lift force becomes equal to the force of gravity.

What does increase stall speed mean?

An increase in stall speed typically means that the aircraft wants you to increase the stall speed by a change either the lift force, surface area of wings, or coefficient of lift. This is all typically done by changing flight angles or the wing flaps.

Is stall speed affected by altitude?

Yes, the stall speed is affected by altitude because the stall speed is directly correlated to air density and the density of air changes with altitude which can be seen in this Air Density Calculator.

Does stall speed increase with altitude?

Since we know that the density of air decreases with altitude and from the formula V = SQRT ( 2* L / (Cl * p * S ), we see that density is inversely proportional to stall speed we can say that stall speed does increase with an increase in altitude.

Stall Speed Example

How to calculate a stall speed?

  1. First, determine the lift force.

    Measure the total force of lift.

  2. Next, determine air density.

    Calculate the density of the air at altitude.

  3. Next, determine the surface area.

    Calculate the surface area of the wings.

  4. Next, determine the coefficient of lift.

    Calculate the coefficient of lift.

  5. Finally, calculate the stall speed.

    Using the equation above, calculate the stall speed.


What is a stall speed?

A stall speed is the slowest velocity a plane can travel and maintain a certain altitude.