Estimate vertical drop from elapsed time or video frame intervals, or solve fall time from a vertical drop, with optional initial vertical velocity. This idealized physics calculation cannot assess jump safety.
Cliff Jump Height Formula
The model uses constant conventional standard gravity, g = 9.80665 m/s2, and ignores air resistance. Blank initial vertical velocity means starting from rest. Positive velocity is downward; negative velocity is upward. The destination must be below the takeoff point.
- h = cliff height or vertical drop distance
- t = fall time
- g = conventional standard gravity, exactly 9.80665 m/s2; v0 = initial downward vertical velocity
Select vertical drop from time, vertical drop from video, or fall time from vertical drop. Video time is elapsed frame intervals divided by the actual recording frame rate; subtract the takeoff frame number from the landing frame number. Slow-motion playback rate is not the recording timebase. Inputs convert to seconds, meters and meters per second. Height is shown in meters and feet; time is shown in seconds. With zero initial velocity, the equations reduce to h = gt²/2 and t = √(2h/g).
Common Cliff Jump Fall Times
These rounded values assume starting from rest, no air resistance, and g = 9.80665 m/s2. They are physics examples, not jump recommendations.
| Height | Height | Fall Time |
|---|---|---|
| 5 m | 16.4 ft | 1.01 s |
| 10 m | 32.8 ft | 1.43 s |
| 20 m | 65.6 ft | 2.02 s |
| 30 m | 98.4 ft | 2.47 s |
Unit Conversions Used
| Unit | Conversion |
|---|---|
| 1 minute | 60 seconds |
| 1 foot | 0.3048 meters |
| 1 meter | 3.28084 feet |
Cliff Jump Height Examples
Example 1: Find height from fall time
You measured a fall time of 2 seconds.
The idealized vertical drop from rest is 19.6133 meters, or about 64.35 feet.
Example 2: Find time from height
You enter a height of 50 feet. First convert feet to meters.
The fall time is about 1.76 seconds.
Cliff Jump Height Calculator FAQ
Does this calculator tell me if a cliff jump is safe?
No. It only calculates height or fall time using a physics formula. It does not account for water depth, submerged rocks, body position, currents, wind, takeoff angle, or landing conditions. Those factors matter for safety but are outside this calculation.
Why does the formula use 9.80665 m/s2?
NIST lists conventional standard gravity as exactly 9.80665 m/s2. Actual local gravity varies. This calculator uses that convention, not a location-specific gravity measurement.
Which inputs do I enter?
Select the quantity to solve for, then complete its visible inputs. Initial vertical velocity is optional and defaults to zero when blank, including when its settings panel is closed. A combination giving zero or negative vertical drop is outside this model.
