Science & Engineering
Free Fall Calculator - Distance, Velocity & Time
Calculate free-fall distance, velocity, or time using h=½gt² and v=gt. Supports metric and imperial.
Free fall formulas
- Distance: h = ½ × g × t²
- Velocity: v = g × t
- Velocity from height: v = √(2 × g × h)
Free fall formulas reference
| Formula | Solves for | Given |
|---|---|---|
| h = ½gt² | Distance fallen | Time and g |
| v = gt | Final velocity | Time and g |
| v² = 2gh | Final velocity | Distance and g |
| t = √(2h/g) | Time to fall | Distance and g |
Gravitational acceleration reference
| Body | g (m/s²) | Compared to Earth |
|---|---|---|
| Earth (standard) | 9.806 | 1× baseline |
| Moon | 1.62 | ~1/6 of Earth |
| Mars | 3.73 | ~0.38× Earth |
| Venus | 8.87 | ~0.91× Earth |
| Jupiter | 24.8 | ~2.5× Earth |
Terminal velocity
In free fall, objects continuously accelerate only in a vacuum. In the real atmosphere, air resistance increases with speed until it equals the gravitational force - at that point the object stops accelerating and falls at a constant terminal velocity. For a human in belly-to-earth skydiving position, terminal velocity is approximately 195 km/h (120 mph). In a head-down dive position, it can reach 290 km/h (180 mph).
Air resistance vs. vacuum
In a vacuum, all objects fall at the same rate regardless of mass - a feather and a hammer fall identically. This was famously demonstrated by Galileo (conceptually) and confirmed live by Apollo 15 astronaut David Scott on the Moon in 1971, who dropped a hammer and a falcon feather simultaneously; both hit the lunar surface at the same time.
Gravitational acceleration
Earth surface: 9.81 m/s² (32.17 ft/s²). The Moon: 1.62 m/s². Mars: 3.72 m/s². Change the g value in the calculator to explore other worlds.