Jump Height from Flight Time Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/10/2026
Vertical jump height is calculated with h = g × t² ÷ 8, where g = 9.81 m/s² and t is the flight time. A flight time of 0.5 seconds corresponds to a jump of about 30.7 cm.
Explanation
Most vertical jump measurement devices (contact mats, photocells, high-frame-rate smartphone apps) don't directly measure height: they measure flight time, the duration during which the feet don't touch the ground. Jump height is then derived from an exact kinematic relationship: during flight, the center of gravity rises then falls symmetrically, so it rises for half the flight time and falls for the other half. Applying the free-fall law to the upward phase gives h = g × t² ÷ 8. This calculation provides the input that several other calculators in this category require without explaining how to obtain it: jump height feeds our vertical jump power calculator (Sayers), which uses it with body mass to estimate the power developed, and it is also the starting point for a reactive strength index once a ground contact time is added. The formula assumes the body position is identical at takeoff and landing (legs extended in both cases): if the athlete tucks their knees under them in the air ("tuck jump" technique), flight time increases without the center of gravity rising any higher, and the calculated height is then overestimated. Jump performance is one facet of fitness; our VO2max calculator covers the aerobic side, using a heart-rate ratio rather than an explosive test.
Example: a flight time of 0.5 seconds
Inputs
Measured flight time: 0.5 s.
Calculation
Height = 9.81 × 0.5² ÷ 8 = 9.81 × 0.25 ÷ 8 ≈ 0.3066 m, about 30.7 cm.
Result
A flight time of 0.5 seconds corresponds to a vertical jump of about 30.7 cm.
Frequently asked questions
Why divide by 8 and not another number?
The 8 comes from combining two factors: the center of gravity only rises for half the flight time (a factor of 2 squared, i.e. 4, in the t²), and the free-fall formula itself has a factor of ½. The product of these factors gives exactly g × t² ÷ 8.
Does the calculated height match what I can touch with my hand?
No, this formula gives the rise of the center of gravity between the standing position with legs extended and the peak of the jump, not the height reached by the outstretched hand. The sporting "reach" (the difference between the height touched with an outstretched arm standing and at the peak of the jump) is generally close to this value, but also depends on the range of shoulder extension.
Can this formula be used with a smartphone app measurement?
Yes, provided the app actually measures flight time frame by frame on a high-frame-rate video (120 or 240 frames per second): accuracy depends directly on the video frame rate. A 30-frames-per-second camera introduces an uncertainty of several centimeters on the height and isn't suitable for precise tracking.