Drag Force Calculation - enter Drag Coefficient

Compute Drag Force, Velocity, or Area


Drag force calculation is mobile-device-friendly as of August 31, 2014

Register to enable "Calculate" button.

Select fluid: 
Select calculation:   
Fluid Density: 
Drag Coefficient, C: 
Reference Area, A: 
Velocity, V: 
Force, F: 
©2014 LMNO Engineering,  Research, and Software, Ltd.  http://www.LMNOeng.com

Units in Drag Force calculator: cm=centimeter, ft=feet, g=gram, hr=hour, kg=kilogram, km=kilometer, lb=pound, m=meter, N=Newton, s=second

Drag force is caused by a fluid (such as water or air; or any liquid or gas) impinging upon an object. The drag force is a function of the fluid velocity and density along with the object's reference area and drag coefficient. The drag coefficient may further be a function of the Reynolds number. Reynolds number depends on the fluid density, viscosity, and velocity as well as the object's characteristic length.

Drag Force Equation (Blevins, 2003 and Munson et al., 1998 and others)

F = 0.5 C ρ A V2

Our calculation allows you to use a variety of units with all of the conversions completed internally. The units below are consistent units for the drag force equation.
A = Reference area as (see figures above), m2.
C = Drag coefficient (see figures above), unitless.
F = Drag force, N.
V = Velocity, m/s.
ρ = Density of fluid (liquid or gas), kg/m3.

Drag coefficients for various objects (photographs taken by LMNO Engineering).

Tree (C values from Munson et al., 1998)
A=Tree frontal area
C=0.43 if V=10 m/s (36.0 km/h, 22.4 mph)
C=0.26 if V=20 m/s (72.0 km/h, 44.7 mph)
C=0.20 if V=30 m/s (108 km/h, 67.1 mph)
Flag (C values from Munson et al., 1998)
C=0.07 if L/D=1
C=0.12 if L/D=2
C=0.15 if L/D=3
Thin Rectangular Plate (C from Blevins, 2003)
Flow coming at the sign
C=1.05 if L/D=1.0
C=1.10 if L/D=2.0
C=1.12 if L/D=4.0
C=1.20 if L/D=8.0
C=1.22 if L/D=10.0
C=1.22 if L/D=12.0
C=1.33 if L/D=17.8
C=1.90 if L/D=infinity
Thin rectangular plate


"Need Density > 0", "Need C > 0", "Need Area > 0", "Need Velocity > 0", "Need Force > 0".

Blevins, Robert D. 2003. Applied Fluid Dynamics Handbook. Krieger Publishing Co.

Munson, Bruce R., Donald F. Young, and Theodore H. Okiishi. 1998. Fundamentals of Fluid Mechanics. John Wiley and Sons, Inc. 3ed.


© 2008-2014 LMNO Engineering, Research, and Software, Ltd.  All rights reserved.

Please contact us for consulting or other questions.

LMNO Engineering, Research, and Software, Ltd.
7860 Angel Ridge Rd.   Athens, Ohio 45701  USA   Phone and fax: (740) 592-1890
LMNO@LMNOeng.com    http://www.LMNOeng.com


LMNO Engineering home page (more calculations)  

Drag Force Calculation with built-in drag coefficient values

Unit Conversions

Trouble printing?