Calculate air friction (drag force) from speed, frontal area and drag coefficient, with typical Cd values for common shapes and sea-level air density.

Area facing the airflow, e.g. width ร— height of the object seen from the front.

Typical values for common shapes. Choose Custom if you know your objectโ€™s Cd.

Standard sea-level air at 15 ยฐC is 1.225 kg/mยณ. Change it for altitude, temperature or another fluid.

Optional settings

Air Friction Formula

The following formula is used to calculate the Air Friction.

Fair = .5 ร— p ร— V2 ร— C ร— A
  • Where Fair is the Air Friction (N)
  • p is the density of the fluid (kg/m3) 
  • V is the speed of the object (m/s) 
  • C is the air resistance coefficient 
  • A is the cross-sectional area (m2)

How to Calculate Air Friction?

The following example problems outline how to calculate the Air Friction.

Example Problem #1

  1. First, determine the density of the fluid (kg/m3). In this example, the density of the fluid (kg/m3) is given as 124.
  2. Next, determine the speed of the object (m/s). For this problem, the speed of the object (m/s) is given as  35.
  3. Next, determine the air resistance coefficient. In this case, the air resistance coefficient is found to be .6.
  4. Next, determine the cross-sectional area. In this example, this is .25m2.
  5. Finally, calculate the Air Friction using the formula above: 

Fair = .5 * p * V2 * C * A

Inserting the values from above yields: 

Fair = .5 * 124 * 352 * .6 * .25 = 11,392.5 (N)

Example Problem #2

Using the same method as above, determine the variables required by the equation. For this example problem, these are as follows:

density of the fluid (kg/m3) = 145

speed of the object (m/s) = 5

air resistance coefficient = .80

cross-sectional area (m2) = .34

Entering these given values and solving gives: 

Fair = .5 * 145 * 52 * .8 * .34 = 493 (N)