By Zencalcy Editorial TeamLast reviewed About us
An object released from rest in a vacuum accelerates downward at standard gravity. Given any one of drop height, fall time or impact velocity, the other two follow from the same three equations. This page covers all three directions in one place.
Time, speed and distance for an object dropped from rest.
h = ½gt² v = gt v² = 2gh
These equations assume zero initial velocity and no air resistance. Real objects reach terminal velocity, which is lower than the vacuum impact speed.
| Symbol | Meaning |
|---|---|
| h | Drop height, in metres. |
| t | Time in free fall, in seconds. |
| v | Impact velocity, in metres per second. |
| g | Standard gravity, 9.80665 m/s². |
From 20 m the fall lasts about 2.019 s and the object reaches roughly 19.80 m/s, ignoring air resistance.
Continue with the Free Fall with Air Resistance Calculator, Friction Calculator, or the Ground Speed Calculator — or browse more kinematics tools and all physics calculators.
No, in a vacuum. All objects accelerate at the same rate regardless of mass because gravitational force scales with mass.
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Free calculator · No signup
Content updated: September 2026