Drag Force Calculator
Drag force opposes the motion of an object through a fluid (air, water, etc.). It is calculated using the drag equation Fd = 0.5 x rho x v^2 x Cd x A. This calculator also determines the power needed to maintain a given speed and the terminal velocity for a falling object.
The drag equation Fd = ½ρv²CdA shows that drag force depends on fluid density (ρ), the square of velocity (v²), the drag coefficient (Cd), and the frontal cross-sectional area (A). Because drag grows with the square of speed, doubling speed quadruples the drag force.
The drag coefficient characterizes the aerodynamic shape of an object. A streamlined teardrop has Cd ≈ 0.04, a modern car about 0.25-0.35, a sphere about 0.47, and a flat plate about 1.28. Reducing Cd is a primary goal of aerodynamic design in automobiles, aircraft, and cycling.
The power to overcome drag is P = Fd × v, which grows with the cube of velocity. This explains why fuel consumption increases dramatically at highway speeds. Terminal velocity is reached when gravitational force equals drag force, and the object stops accelerating: vt = √(2mg / ρCdA).