Free-Fall Time Calculator
Time = √(2 × distance ÷ gravity)
Estimate time to fall from rest through a specified distance.
Formula
Time = √(2 × distance ÷ gravity)
Worked example
Fall distance: 20 m
Gravity: 9.80665 m/s²
With these inputs, the result is 2.01961998 s.
How to use this calculator
- Identify the quantity you want to calculate.
- Enter your measurements in the units shown on each field.
- Read the result, which updates as you change the inputs.
- Check the assumptions below before applying the result.
Assumptions and limits
Air resistance is excluded. This is an idealized physics calculation, not a safety assessment.
Precision and checking
Results are rounded for display. Use the most accurate measurements available, and avoid rounding your inputs unnecessarily. Extra decimal places in a result do not make an estimate more reliable.
To check a result, substitute the same input values into the formula shown above. Change one value at a time to understand how the quantity responds.
Frequently asked questions
What assumptions does this calculation use?
Air resistance is excluded. This is an idealized physics calculation, not a safety assessment.
Are my inputs sent to a server?
No. The calculation runs locally in your browser. The result updates as you edit the inputs.
Sources & references
- NIST Guide to the SI — National Institute of Standards and Technology
