Free Fall Calculator
By Santaji GadepatilinUpdated October 27, 2026
In free fall, gravity is the only force acting, so every object speeds up at the same rate — about 9.81 m/s² near Earth's surface. This lets you work out fall time, distance and impact speed.
Impact speed (m/s) vs Fall height (m) — other inputs held at your current values.
How to use the free fall calculator
Enter the height, the fall time or the impact speed — the other two are calculated. Results ignore air resistance, which is accurate for short drops of dense objects.
Free fall formulas
h = ½ g t² v = g t v = √(2gh)
Worked example
A stone dropped from 20 m:
- t = √(2 × 20 ÷ 9.81) = 2.02 s
- v = 9.81 × 2.02 = 19.8 m/s (71 km/h)
Air resistance and terminal velocity
Real objects do not keep accelerating. Air resistance grows with speed until it balances weight, and the object falls at terminal velocity:
| Object | Approximate terminal velocity |
|---|---|
| Raindrop | 9 m/s (32 km/h) |
| Skydiver, belly down | 55 m/s (200 km/h) |
| Skydiver, head down | 80–90 m/s (300 km/h) |
| Feather | under 1 m/s |
The calculator ignores air resistance, so it is accurate for short drops of dense objects, but overestimates speed for long falls.
Time and speed for each second
| Time | Distance fallen | Speed |
|---|---|---|
| 0.5 s | 1.2 m | 4.9 m/s (18 km/h) |
| 1 s | 4.9 m | 9.8 m/s (35 km/h) |
| 1.5 s | 11.0 m | 14.7 m/s (53 km/h) |
| 2 s | 19.6 m | 19.6 m/s (71 km/h) |
| 3 s | 44.1 m | 29.4 m/s (106 km/h) |
| 4 s | 78.5 m | 39.2 m/s (141 km/h) |
| 5 s | 122.6 m | 49.0 m/s (177 km/h) |
Distance grows with the square of time: in 2 seconds an object falls four times as far as in 1 second.
Galileo’s insight
Without air resistance, all objects fall at the same rate regardless of mass. Astronaut David Scott demonstrated this on the Moon in 1971 by dropping a hammer and a feather, which landed together.
Measuring a well’s depth
Drop a stone and time the splash. If it takes 2 s, the depth is about 19.6 m (a little less once you allow for the time sound takes to travel back up).
Fall distances
| Time | Distance | Speed |
|---|---|---|
| 1 s | 4.9 m | 9.8 m/s |
| 2 s | 19.6 m | 19.6 m/s |
| 3 s | 44.1 m | 29.4 m/s |
| 4 s | 78.5 m | 39.2 m/s |
Frequently asked questions
How long does it take to fall 20 m?
About 2.02 seconds, reaching about 19.8 m/s (71 km/h), ignoring air resistance.
Do heavy objects fall faster?
Not in a vacuum — all objects accelerate at the same rate. In air, drag slows light or large objects more.
What is terminal velocity?
The speed at which air resistance balances gravity. For a skydiver in a belly-down position it is about 200 km/h.
How long does it take to fall 100 m?
About 4.5 seconds, ignoring air resistance, reaching about 44 m/s.
Does a heavier object fall faster?
Not in a vacuum. In air, heavier dense objects are less slowed by air resistance, so they can reach the ground sooner.