Terminal Velocity Calculator

A falling object stops accelerating when the air pushing up matches its weight. Terminal velocity is the speed where those two forces balance.

MassThe mass of the falling object, in kilograms.GravityThe acceleration of gravity in metres per second squared.Air densityThe density of the air in kilograms per cubic metre. Sea level at 15 degrees is 1.225.Drag coefficientA shape factor. About 1 for a human body, 0.47 for a smooth sphere.Presented areaThe cross section facing the flow, in square metres.

Terminal velocity

42.7763

In kilometres per hour: 153.9947
In miles per hour: 95.6879
Time constant: 4.362
Drag force at that speed: 784.532

Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.

The formula this calculator uses

v = sqrt(2 x m x g / (rho x Cd x A))

v: The terminal velocity, the speed where acceleration stops
m: The mass of the falling object
rho: The density of the air it falls through
Cd x A: The drag coefficient times the presented area

How to check the result by hand

1
Multiply the weight terms
Two times 80 kilograms times 9.80665 is 1569.064. This is twice the weight, and it sits in the numerator of the formula.
2
Multiply the drag terms
Air density times the drag coefficient times the area is 1.225 times 1 times 0.7, which is 0.8575. This is the denominator.
3
Divide and take the square root
1569.064 divided by 0.8575 is 1829.8122, and the square root of that is 42.7763 metres per second.
4
Confirm the forces balance
At that speed drag is 784.532 newtons, which is exactly the weight of an 80 kilogram mass. The balance confirms the speed is terminal.

For worked examples, common mistakes and the limits of this formula, read the full How To Calculate Terminal Velocity page.