Updated Physics & Engineering Tool

Free Fall Time Calculator

Compute time to fall, distance fallen and impact velocity for dropped or thrown objects under constant gravity. Switch between basic free fall, initial velocity, distance–time relationships and quick comparison tables with gravity presets.

Time to impact Distance fallen Impact velocity Earth, Moon, Mars & more

Multi-Mode Free Fall Time Calculator

Use the tabs to analyze free fall for dropped objects, motion with initial velocity, distance fallen after a given time or time required to fall a specified distance. Choose gravity presets for Earth, Moon, Mars or enter a custom value.

For most problems on Earth you can use g = 9.8 m/s² or the standard value 9.80665 m/s².

This mode assumes the object is dropped from rest from the specified height. The time to impact is t = √(2h / g), and the impact speed is v = gt, ignoring air resistance.

Positive = upward, negative = downward.

The vertical position is y(t) = h0 + v0 t − ½ g t². The calculator finds the positive time when y(t) returns to zero and then reports total flight time, maximum height and impact speed.

In pure free fall from rest, distance after time t is d = ½ g t² and velocity is v = gt. This tab focuses on the distance–time relationship, independent of any specific starting height.

For an object dropped from rest, the time to fall distance d under gravity g is t = √(2d / g) and the speed at that moment is v = √(2gd). This is essentially the inverse of the distance-from-time mode.

Gravity strongly affects how quickly objects fall. Use the presets above to change g and then compare drop times from different heights in the quick comparison table below.

Common Gravity Values (m/s²)

Environment Approximate g Notes
Earth (sea level) 9.80665 Standard gravity used in most physics problems and engineering approximations.
Moon 1.62 About 1/6 of Earth’s gravity; objects fall more slowly and travel higher for the same launch speed.
Mars 3.71 Roughly 38% of Earth’s gravity; useful for planetary science and space exploration examples.
Jupiter (cloud tops) 24.79 More than twice Earth’s gravity; free fall times are much shorter.
Custom Your value Enter any positive value for g to explore hypothetical or other-world scenarios.

Quick Comparison – Drop Time from Common Heights

This table uses the current gravity value and height unit to estimate time to fall and impact speed from several standard heights, assuming the object is dropped from rest.

Drop height Time to fall Impact speed

Free Fall Time Calculator – Ideal Vertical Motion Under Gravity

When you drop an object or throw it straight up, its subsequent motion under gravity follows a simple set of equations. This Free Fall Time Calculator helps you explore those equations interactively. You can compute how long an object takes to fall, how far it travels and how fast it is moving when it reaches a specific point, with options for initial velocity and different gravitational fields.

The calculator assumes constant gravitational acceleration and no air resistance. That matches most classroom physics problems and provides a clean starting point for more advanced modeling with drag or wind.

Basic Free Fall from Rest

For an object dropped from rest from height h under gravity g, the vertical position as a function of time t is:

y(t) = h − ½ g t²

Setting y(t) = 0 (ground level) and solving for t gives the time to impact:

  • Time to fall: t = √(2h / g)
  • Impact speed: v = gt
  • Distance fallen at time t: d(t) = ½ g t²

The basic free fall tab implements these formulas, converting heights and velocities between metric and imperial units as needed.

Free Fall with Initial Velocity

If the object is thrown upward or downward with initial vertical velocity v0 from height h0, the vertical position is:

y(t) = h0 + v0 t − ½ g t²

The calculator finds the positive solution of y(t) = 0 to obtain the total flight time. The maximum height occurs when the vertical velocity becomes zero, at time tpeak = v0 / g (for upward v0). The additional rise is v0² / (2g), so:

  • Maximum height: hmax = h0 + v0² / (2g) (if v0 > 0)
  • Impact speed: found from v = v0 − gt or via energy: v² = v0² + 2gh0

Distance–Time and Time–Distance Relationships

The distance-fallen and time-from-distance modes focus on the core kinematic relationships for free fall from rest:

  • Distance from time: d = ½ g t²
  • Time from distance: t = √(2d / g)
  • Instantaneous speed: v = gt or v = √(2gd)

These equations are widely used in physics, engineering and everyday estimates such as how long it takes an object to fall from a balcony or a cliff in an idealized scenario.

Gravity Presets and Comparisons

Gravity varies from one celestial body to another. The calculator includes presets for:

  • Earth: 9.80665 m/s² (standard gravity)
  • Moon: 1.62 m/s²
  • Mars: 3.71 m/s²
  • Jupiter: 24.79 m/s²

A quick comparison table shows how fall time and impact speed change for common heights under the currently selected gravity and unit system. This is especially useful for teaching and for visualizing how different planetary environments affect motion.

How to Use the Free Fall Time Calculator

  • Use the Basic Free Fall tab when an object is simply dropped from rest from a known height.
  • Switch to Free Fall with Initial Velocity when the object is thrown upward or downward before falling.
  • Use Distance Fallen After Time to explore how far an object falls in a given time interval.
  • Use Time to Fall a Given Distance for the inverse problem: how long it takes to fall a specified distance.
  • Experiment with gravity presets and the comparison table to see how the same drop behaves on different worlds.

Always keep in mind that this calculator does not include air resistance. Real objects, especially light or large-area ones, will fall more slowly and may reach a terminal velocity where drag balances gravity.

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Free Fall Motion FAQs

Frequently Asked Questions About Free Fall Time and Distance

Key concepts behind ideal free fall under constant gravity.

In the ideal physics model without air resistance, gravitational acceleration is independent of mass, so all objects fall with the same acceleration g. In the real world air resistance can make lighter or less dense objects fall more slowly, but that effect is not included here.

Yes. You can choose feet or meters (and even kilometers or miles) for distance, and select m/s, ft/s, km/h or mph for velocity. The calculator converts everything to SI units for computation and then back into your chosen units for display.

The formulas used for free fall require positive gravity. The calculator checks for non-positive values of g and prevents the calculation if gravity is less than or equal to zero. Make sure to use realistic positive values like those in the preset list.

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