By Zencalcy Editorial TeamLast reviewed About us
Drag grows with the square of speed, so doubling your speed quadruples the resisting force. This calculator applies the standard drag equation using the fluid's density, the object's frontal area and its drag coefficient, and can also work backwards from a known drag to the speed that causes it.
Aerodynamic drag from speed, area and drag coefficient.
F = ½ ρ v² C_d A
ρ is fluid density in kg/m³, v is speed relative to the fluid, C_d is the dimensionless drag coefficient and A is the frontal area. Sea-level air is about 1.225 kg/m³.
| Symbol | Meaning |
|---|---|
| F | Drag force, in newtons, opposing the motion. |
| ρ | Density of the fluid, in kg/m³. |
| v | Speed of the object relative to the fluid, in m/s. |
| C_d | Drag coefficient, dimensionless; about 0.47 for a sphere. |
| A | Frontal (reference) area, in m². |
With ρ = 1.225 kg/m³, v = 30 m/s, C_d = 0.47 and A = 0.5 m², the drag is 0.5 × 1.225 × 900 × 0.47 × 0.5 = 129.5 N.
Continue with the Force Calculator, Gravitational Force Calculator, or the Impact Force Calculator — or browse more dynamics tools and all physics calculators.
Each second the object sweeps through a volume proportional to its speed, and each unit of air must be accelerated to a speed also proportional to v. The momentum change per second therefore scales with v².
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026