Case 1
- Mass
- 80kg
- Frontal area
- 0.7m²
- Drag coefficient
- 1
- Fluid density
- 1.225kg/m³
42.78m/s
Open with these valuesTerminal Velocity Calculator
42.78m/s
Result: 42.78 m/sTerminal velocity is where drag exactly cancels weight, so the fall stops speeding up. All four inputs sit under a square root, which is why doubling the mass only raises the speed by about 41 %. The drag coefficient is the shape: 1.0 for a skydiver belly-to-earth, 0.7 head-down, 0.47 for a sphere.
Worked examples
Case 2
- Mass
- 80kg
- Frontal area
- 0.18m²
- Drag coefficient
- 0.7
- Fluid density
- 1.225kg/m³
100.82m/s
Open with these valuesCase 3
- Mass
- 0.0445kg
- Frontal area
- 0.00143m²
- Drag coefficient
- 0.47
- Fluid density
- 1.225kg/m³
32.56m/s
Open with these valuesHow it's calculated
v = √(2 × m × g ÷ (ρ × A × Cd)), g = 9.80665 m/s²
- StepEnter the mass in kilograms.
- StepEnter the frontal area the object presents to the airflow, in m².
- StepPick a drag coefficient for the shape — 0.47 sphere, 1.0 skydiver flat.
- ResultEnter the fluid density: 1.225 kg/m³ for air at sea level.
Reference table
| Mass, area, Cd, density | Falling object | Speed (m/s) |
|---|---|---|
| 0.0445, 0.00143, 0.47, 1.225 | Golf ball | 32.56 |
| 1, 1, 1, 1.225 | One square metre, one kilogram | 4.00 |
| 80, 0.7, 1, 1.225 | Skydiver belly-to-earth | 42.78 |
| 100, 1, 0.5, 1.225 | Generic blunt body | 56.59 |
| 80, 0.18, 0.7, 1.225 | Skydiver head-down | 100.82 |
Questions
How do I calculate terminal velocity?
Take the square root of twice the mass times gravity, divided by the product of fluid density, frontal area and drag coefficient: v = √(2 × m × g / (ρ × A × Cd)). With g = 9.80665 m/s², an 80 kg skydiver at 0.7 m², drag coefficient 1, in air of 1.225 kg/m³ reaches about 42.78 m/s.
What is terminal velocity?
Terminal velocity is the constant speed a falling object reaches when air resistance grows large enough to exactly balance its weight. At that point the net force is zero, so the object stops accelerating and falls at a steady speed rather than getting ever faster.
What is a skydiver's terminal velocity?
A skydiver falling belly-to-earth levels off at roughly 50 to 55 m/s, about 190 km/h, because the spread-out posture presents a large frontal area. Diving head-down with a small area pushes the terminal velocity well past 90 m/s.
What affects terminal velocity?
Four things: a heavier mass raises it, while a larger frontal area, a higher drag coefficient (a less streamlined shape) and a denser fluid all lower it. Because all four sit inside a square root, doubling any one of them changes the speed by only about 41 %.
Which drag coefficient should I use?
It is a measured value for a shape, not a constant: a sphere is about 0.47, a skydiver spread flat about 1.0, the same skydiver head-down about 0.7, and a generic blunt body around 0.5. Streamlined shapes go far lower — a modern car sits near 0.3.
What units should I use?
Kilograms for mass, square metres for area, a dimensionless drag coefficient and kg/m³ for fluid density; air at sea level is 1.225. The result comes out in metres per second, so multiply by 3.6 to read it as km/h.
Sources and last check
Information, not professional advice.