Free Fall Time Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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A short mechanics equation can tell you a lot—provided the sign convention and idealizations are clear. Free Fall Time Calculator is built around free-fall time, so the useful result stays connected to the motion or force relationship that produces it.

What this calculator does

The Free Fall Time Calculator centers on free-fall time using the fields that are actually present here: Gravitational acceleration (g), Initial velocity (v₀), Height (h), Velocity (v), Time of fall (t). Rather than treating every box as an independent input, use the equation below to identify the driving quantities and read the remaining fields as derived or supporting values when appropriate.

How to use it

Enter height, g, and initial velocity. Leave time blank so it can be derived; the velocity field is filled as a supporting result.

How the calculation works

For a known fall height h and initial downward velocity v₀, the page uses v² = v₀² + 2gh and then t = (v−v₀)/g. From rest this reduces to t = √(2h/g).

Example

A 20 m fall from rest at g = 9.80665 m/s² takes about √(40/9.80665) = 2.02 s. The ideal final speed is about 19.81 m/s.

How to interpret the result

For Free Fall Time Calculator, read free-fall time in the context of the equation above. Interpret the result within the stated ideal mechanical model. Check whether doubling the driving force, time, length, or other key variable changes the result in the way the equation predicts; that directional check often catches unit and sign mistakes before the decimal places matter.

Limitations and notes

The computed time is an ideal vacuum-style result with constant g. Air drag usually lengthens the fall time, especially for low-density or high-area objects. The page also assumes the entered height is reachable under the chosen initial velocity and sign convention.