Terminal Velocity Calculator
Find the maximum falling speed through a fluid.
Dimensionless; ~1.0 for a spread skydiver, ~0.5 for a sphere.
Defaults to air at 1.225 kg/m³.
Defaults to Earth's 9.81 m/s².
Results update as you type.
How it works
Terminal velocity is the constant maximum speed an object reaches as it falls through a fluid such as air, when the upward drag force finally balances the downward pull of gravity. This terminal velocity calculator computes it from the object's mass, its drag coefficient, its cross-sectional area, and the fluid density. Once these forces balance, the object stops accelerating and falls at a steady speed, which is why a skydiver does not keep speeding up indefinitely. This matters in skydiving, ballistics, meteorology, and engineering. It explains why a spread-eagled skydiver falls at around 120 miles per hour but slows dramatically once a parachute vastly increases area and drag, why raindrops of different sizes hit the ground at survivable speeds, and how designers predict the descent of everything from seeds to spacecraft. A terminal velocity calculator lets you explore how mass, shape, and air density each shift that limiting speed. The formula works because drag force increases with the square of speed, so an object accelerates only until drag equals its weight, then falls steadily. Heavier or more streamlined objects reach higher terminal velocities, while larger frontal area, denser fluid, or a blunter shape lowers it. Physics students, skydivers, and engineers use a terminal velocity calculator to understand and predict how objects settle into their steady falling speed.
vₜ = √( 2·m·g ÷ (ρ·A·C_d) )
Terminal velocity is the steady speed a falling object reaches when air resistance grows strong enough to exactly balance gravity, so acceleration stops. Setting the drag force equal to weight and solving for speed gives the square root of twice the weight divided by the product of fluid density, cross-sectional area, and drag coefficient. The formula works because drag rises with the square of speed, so a falling object accelerates only until drag catches up with its weight; a heavier object needs more speed to generate matching drag, while a larger or blunter shape reaches balance sooner.
Source:Standard physics (drag equation)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter mass, drag coefficient and cross-sectional area.
- 2
Adjust the options
Adjust fluid density and gravity if they apply — sensible defaults are already set.
- 3
Read your result
Terminal velocity updates instantly as you type — no button to press.
Frequently asked questions
Why does a falling object stop accelerating?
As an object falls, air resistance, or drag, increases with the square of its speed. It keeps accelerating until the upward drag force grows large enough to exactly cancel the downward force of gravity. At that point the net force is zero, so by Newton's second law the acceleration is zero and the object falls at a constant speed, its terminal velocity, for the rest of the descent.
What is the drag coefficient and what value should I use?
The drag coefficient is a dimensionless number describing how streamlined a shape is, with lower values meaning less resistance. A smooth sphere is about 0.5, a flat plate facing the flow around 1.1, and a belly-to-earth skydiver roughly 1.0. Streamlined shapes like a diving falcon or a bullet have much smaller coefficients. Choose a value that matches your object's shape and orientation for an accurate terminal velocity.
Why do heavier objects fall faster in air?
In a vacuum, all objects fall at the same rate regardless of mass, but in air, drag depends on size and shape rather than mass. A heavier object of the same shape must reach a higher speed before drag grows enough to balance its greater weight, so it settles at a higher terminal velocity. This is why a marble falls faster than a feather in air, even though they would drop together in a vacuum.
How does a parachute change terminal velocity?
A parachute dramatically increases both the cross-sectional area and the effective drag coefficient of a falling system. Because terminal velocity is inversely proportional to the square root of area and drag coefficient, this large increase sharply reduces the steady falling speed. A skydiver falling at roughly 55 metres per second can slow to around 5 metres per second under an open canopy, making a safe landing possible.
What fluid density should I enter?
For an object falling through air at sea level, use about 1.225 kilograms per cubic metre, which is this calculator's default. Air is thinner at high altitude, lowering density and raising terminal velocity, while denser fluids like water dramatically reduce it. If you are modelling a fall through water, use roughly 1,000 kilograms per cubic metre instead, and the object will reach a far lower steady speed.