Drag Force Calculator

Work out drag force instantly with clear inputs, formula shown and shareable results.

About Drag Force Calculator

Drag grows with the square of speed: F = 0.5 rho v^2 Cd A. A car with Cd 0.32 and 2.2 m2 frontal area at 100 km/h meets about 333 N of air resistance, needing 9.2 kW just to push the air aside. Because power is drag times speed, it grows with the cube of speed - the reason motorway cruising dominates fuel use.

Formulas

Drag force

F = 0.5 x rho x v^2 x Cd x A

Power

P = F x v, so P scales as v^3

Worked example

With the default values below, Drag Force Calculator returns Drag Force of 332.77. Change any input above and every figure here is recalculated in your browser.

Inputs used

Drag coefficient Cdminimum 0: 0.32
Frontal areaminimum 0 m2: 2.2 m2
Speed through the fluidminimum 0 m/s: 27.78 m/s
Fluid densityminimum 0 kg/m3: 1.225 kg/m3

Results

Drag Force: 332.77 N
Power Needed To Push Through: 9,244.3 W
Same Power In Kilowatts: 9.2443
Effective Drag Area CdA: 0.7040 m2

Step by step

1Values used
2Drag force
3Power
4Drag Force= 332.77 N
5Power Needed To Push Through= 9,244.3 W
6Same Power In Kilowatts= 9.2443
7Effective Drag Area CdA= 0.7040 m2

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is CdA quoted rather than Cd alone?

Because drag depends on both. A slippery but large vehicle can have more drag than a boxy small one, and CdA captures the combination.

What are typical drag coefficients?

About 0.25-0.35 for modern cars, 0.5-0.7 for a cyclist upright, 0.04 for an aerofoil, and 1.1-1.3 for a flat plate.