Vertical Jump Calculator
Jump height and takeoff speed from flight time, metric or imperial.
What it does
Hang time tells jump height through gravity alone. Splitting flight evenly between rise and fall gives height as g times time squared over 8, so 0.6 seconds airborne means 44.1 cm up with a 2.94 m/s launch. The tool above converts any flight time in either unit system.
The metric default is a solid recreational jump: 0.60 s, 44.1 cm, 17.4 in beside it. Imperial mode reads a 0.55 s flight as 14.6 in with an 8.8 ft/s launch. Both assume the center of mass lands exactly as high as it left.
Biomechanics literature runs the same equation. A sports medicine review derives height as g times flight squared over 8 from constant acceleration, and jump mat studies validate the flight time formula within a few percent when posture holds. Published error work warns bent knee landings can overread by tens of percent.
Posture is the whole method. Tucked legs at landing stretch flight without extra height, and arm swing timing shifts takeoff speed readings on plates. Test on flat ground with matched takeoff and landing shapes, and treat single best jumps as noise beside rolling averages.
How to use
- Pick metric (cm) or imperial (in).
- Measure flight time from takeoff to landing.
- Type the seconds into the tool.
- Read jump height first.
- Read takeoff speed to compare power.
Formula
- t
- Total flight time in seconds.
- h
- Center of mass rise.
- v
- Vertical speed at takeoff.
Vacuum gravity math; air drag trims real jumps slightly. Equal takeoff and landing heights required, or the split halves mislead.
Worked example
Example: 0.6 s flight
Metric default: flight 0.6 s.
- Square: 0.6 x 0.6 = 0.36.
- Height: 9.80665 x 0.36 / 8 = 0.4413 m = 44.1 cm.
- Takeoff: 9.80665 x 0.6 / 2 = 2.94 m/s.
- Inches: 0.4413 x 39.3701 = 17.4 in.
- Tool shows 44.1 cm, 2.94 m/s, 17.4 in.
Reference table
| Flight | Height | Takeoff |
|---|---|---|
| 0.4 s | 19.6 cm | 1.96 m/s |
| 0.5 s | 30.6 cm | 2.45 m/s |
| 0.6 s | 44.1 cm | 2.94 m/s |
| 0.7 s | 60.1 cm | 3.43 m/s |
Limits
- Matched posture required at both ends.
- Air drag ignored; real jumps read a touch lower.
- Mat timing errors square into height errors.
- One jump is noise; average several.
Common mistakes
- Landing tucked and claiming the extra inches.
- Timing from video at low frame rates.
- Comparing mat numbers with reach tests.
- Ignoring arm swing differences.
- Chasing single best instead of average.
Try it yourself
Quick checks. Answers sit tucked under each question.
0.5 s flight?
9.80665 x 0.25 / 8 = 0.3065 m = 30.6 cm.
0.7 s flight?
9.80665 x 0.49 / 8 = 0.6007 m = 60.1 cm.
0.55 s flight in inches?
0.3708 m = 14.6 in at 8.8 ft/s takeoff.
Questions
How high is 0.6 s?
44.1 cm with a 2.94 m/s launch.
Why divide by 8?
Half the flight rises: 0.5 x g x (t/2) squared simplifies there.
Does landing posture matter?
Yes. Bent knees stretch flight and inflate height.
What is a good jump?
Near 40 to 50 cm marks strong recreational legs.
Reach test or flight time?
Different measures; do not mix their numbers.
Why average jumps?
Timing noise squares, so means beat bests.