About this tool
Terminal Velocity Calculator is a free, in-browser physics tool that finds the steady speed a falling object reaches when air (or fluid) drag balances gravity. Enter the mass, drag coefficient, cross-sectional area and fluid density, and it returns the terminal velocity in several units plus the balancing force. Everything is computed locally in your browser.
At terminal velocity the drag force equals the weight, ½·ρ·v²·A·Cd = m·g, which rearranges to vₜ = √(2·m·g / (ρ·A·Cd)). Here ρ is the fluid density (air ≈ 1.225 kg/m³, water ≈ 1000), A is the frontal area, Cd is the drag coefficient (≈ 0.47 for a sphere, ≈ 1.0 for a belly-down skydiver) and g = 9.81 m/s². The tool can also solve for any one variable when the others are known.
Use it to estimate how fast a skydiver, raindrop or dropped object falls. Terminal velocity is shown in metres per second, kilometres per hour and miles per hour, with mass in kg, area in m² and density in kg/m³.
Frequently asked questions
What is the terminal velocity formula?
Setting drag equal to weight gives vₜ = √(2·m·g / (ρ·A·Cd)), where m is mass, g = 9.81 m/s², ρ is the fluid density, A the cross-sectional area and Cd the drag coefficient. At this speed the net force is zero, so the object stops accelerating.
What drag coefficient and density should I use?
For air use ρ = 1.225 kg/m³ (water is about 1000). A smooth sphere has Cd ≈ 0.47 and a belly-down skydiver about 1.0. The presets fill these in, and you can override any value.
Can it solve for mass or area instead?
Yes. Switch the 'solve for' selector to mass, drag coefficient, area or density, enter the terminal velocity and the remaining values, and it inverts the formula to find the unknown.
Why does drag force equal weight at terminal velocity?
As speed rises, drag (which grows with v²) increases until it exactly cancels the downward weight m·g. With zero net force the object stops accelerating, so the drag force at terminal velocity equals the weight. All math runs in your browser.
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