Drag Force Calculator
Force goes as v², power goes as v³.
Work out Drag Force. Force goes as v², power goes as v³. Shows the working, not just the answer.
Modern car 0.3, cyclist 0.9, sphere 0.47, flat plate 1.28.
Optional — gives the deceleration drag alone would cause.
Drag force
363.83 N
10.915 kW to overcome it at this speed
F = ½ρv²CdA. Force grows with the square of speed, but the POWER needed grows with the cube, because power is force times velocity. Doubling a car's speed quadruples the drag and takes eight times the engine power to hold. That cubic relationship is most of why fuel economy collapses above about 100 km/h, and why the last few km/h of top speed cost so much more than the first.
How the Drag Force Calculator works
Enter drag coefficient, fluid density, frontal area and speed for the drag force and the power needed to hold that speed. The cubic power relationship is why fuel economy falls apart on the motorway.
Also known as: air resistance calculator · aerodynamic drag calculator · drag equation calculator · power to overcome drag
Frequently asked questions
What is the drag equation?
F = ½ρv²CdA. Force rises with the square of speed, the fluid density, the drag coefficient and the frontal area.
Why does power grow faster than force?
Because power is force times velocity, so a v² force needs v³ power. Doubling speed quadruples drag and takes eight times the engine output to sustain.
What is a typical drag coefficient?
A modern car is around 0.3, a cyclist about 0.9, a sphere 0.47 and a flat plate 1.28. Lower is better, but frontal area matters just as much and is often the easier thing to reduce.
Why does fuel economy collapse at speed?
At town speeds most energy goes to rolling resistance and acceleration. Above roughly 80 km/h aerodynamic drag dominates, and its cubic power demand means small speed increases cost a great deal of fuel.
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