Terminal Velocity Calculator
Calculate the terminal velocity of a falling object from its mass, drag and area.
Assumptions used in this calculation
- Constant air density: Assumes constant air density throughout the fall, in reality density decreases with altitude, so actual terminal velocity varies during a long fall.
About this calculator
A skydiver in free fall doesn't keep accelerating forever, air resistance grows with speed until it exactly cancels gravity, and predicting the constant "terminal" speed that results requires balancing two opposing forces that both depend on the falling object's shape and the surrounding air. This calculator computes terminal velocity from mass, drag coefficient (a shape-dependent constant describing how streamlined the object is), cross-sectional area facing the airflow, and air density, using v = √(2mg ÷ (ρ × A × Cd)). Because drag force scales with velocity squared while gravity stays constant, solving for the speed where they balance means working with a square root of a ratio involving four separate variables, not a calculation to eyeball. It's useful for estimating skydiving speeds at different body positions (belly-to-earth versus head-down dramatically changes drag coefficient and area), or any falling-object scenario where drag matters. Air density is treated as constant, though it actually decreases with altitude, so terminal velocity varies somewhat across a long fall.
Worked example
80kg skydiver, belly-to-earth
Result: ~44.7 m/s (161 km/h)
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