Terminal Velocity Calculator
What the Terminal Velocity Calculator does
Drop anything and it will not keep speeding up forever. Drag grows with the square of speed until it balances weight, and from that moment the object falls at a constant terminal velocity. This calculator finds that limit from Mass, Cross-section area, Drag Coefficient, Air density and Gravity.
Skydivers use it to plan body positions, engineers apply it to rain, hail and falling sensors, and students use it to see why a feather loses to a hammer. Meteorologists even use it when modeling raindrop sizes.
The drag balance formula
Terminal velocity follows v = sqrt(2mg/(rho A Cd)), where m is mass, A the cross-section area, Cd the drag coefficient and rho the air density, about 1.225 kg/m3 at sea level. Balance means weight mg equals drag 0.5 rho v^2 A Cd, solved for v.
Take an 80 kg skydiver lying flat with A = 0.5 m2 and Cd = 1.0: v = sqrt(2 x 80 x 9.81 / (1.225 x 0.5 x 1.0)) = sqrt(2562.6), about 50.6 m/s. That lands near the classic 53 m/s human figure. A head-down dive trims the area and pushes past 90 m/s.
How to use the calculator
Start with Mass in kilograms. Enter Cross-section area in square meters, roughly 0.5 to 0.8 for a spread adult body, then the Drag Coefficient, about 1.0 for a blunt shape or 0.5 for something rounder.
Leave Air density at 1.225 kg/m3 for sea level or lower it for altitude, keep Gravity at 9.81 m/s2, then run the calculation. Tip: terminal velocity scales with the square root of your inputs, so doubling area cuts the speed by only 29 percent.
Frequently Asked Questions
What is terminal velocity for a human?
A belly-to-earth skydiver falls at roughly 53 m/s, about 190 km/h. Tucked head-down positions reduce drag and can exceed 90 m/s in freefall.
Does mass affect terminal velocity?
Yes. Speed rises with the square root of mass, so an object twice as heavy with the same area and drag falls about 1.41 times faster.
Why does a feather fall slower?
Its large area and low weight give a tiny mass-to-drag ratio. Its terminal velocity may sit under 1 m/s, so air stops it accelerating almost immediately.
What drag coefficient should I use?
Use about 1.0 for a blunt flat body facing the flow, 0.47 for a sphere, and 0.04 for a highly streamlined shape like an aircraft body.
Does altitude change terminal velocity?
Yes. Thinner air at altitude lowers density, so a skydiver falls faster high up and slows again entering denser air lower down.