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Calculation Machine

Free Fall Time Calculator

Fall time and impact speed from height.

Reviewed by the Calculation Machine team · How we check our maths

Your values

ⓘ Live results

Results
Fall time
2.02 s
Impact speed
19.81 m/s
Impact speed
71.3 km/h
Impact speed
44.3 mph

Quick answer

Fall time = sqrt(2h/g); impact speed = g x t.

The formula

t = sqrt(2h/g)

Worked example

Worked example

Using the values the calculator loads with.

Inputs

  • Drop height20 m
  • Initial velocity0 m/s, down positive

Result

  • Fall time2.02 s
  • Impact speed19.81 m/s
  • Impact speed71.3 km/h
  • Impact speed44.3 mph

How to use the Free Fall Time Calculator

  1. 1Enter the drop height in metres.
  2. 2Add an initial downward velocity if the object was already moving.
  3. 3Read the fall time and impact speed.

Frequently asked questions

Does mass affect fall time?

No — in a vacuum all objects fall at the same rate regardless of mass.

What about air resistance?

Light or wide objects like paper fall slower than this ideal model predicts.

About this calculator