Measuring a vertical jump
The vertical jump is a classic test of leg power used in basketball, volleyball, football combines and fitness testing. There are two common ways to measure it:
- Reach method: mark your standing reach with one arm extended, then jump and mark the highest point. The difference is your jump height.
- Hang time: many jump mats and phone apps measure the time in the air. Since the body rises and falls symmetrically, the height is h = g × t² ÷ 8.
Peak power
The Sayers equation (1999) estimates peak leg power from jump height and body mass:
Power (W) = 60.7 × height (cm) + 45.3 × mass (kg) − 2,055
Takeoff velocity comes from basic physics: v = √(2 g h).
Worked example
An athlete weighing 175 lb (79.4 kg) has a hang time of 0.60 s.
- Jump height: 9.81 × 0.60² ÷ 8 = 0.441 m, or 44.1 cm (17.4 in).
- Takeoff velocity: √(2 × 9.81 × 0.441) = 2.94 m/s.
- Peak power: 60.7 × 44.1 + 45.3 × 79.4 − 2,055 = 4,220 W.
- Power per kilogram: 53.2 W/kg.
Benchmarks
| Level | Men | Women |
|---|---|---|
| Below average | under 16 in (40 cm) | under 12 in (30 cm) |
| Average | 16 to 20 in | 12 to 16 in |
| Good | 20 to 24 in | 16 to 20 in |
| Very good | 24 to 28 in | 20 to 24 in |
| Excellent | over 28 in (70 cm) | over 24 in (60 cm) |
Elite basketball and volleyball players often reach 30 to 40 inches with a running approach.
Improving your jump
- Strength: squats, deadlifts and hip thrusts build the force base.
- Plyometrics: box jumps, depth jumps and bounding train the stretch-shortening cycle.
- Technique: a quick countermovement and a strong arm swing add several centimeters.
- Body composition: extra body fat lowers jump height, even if absolute power stays the same.
- Recovery: jump training is intense; two or three sessions a week are enough.
Accuracy
Hang-time devices assume you land in the same position as you take off. Bending the knees or hips on landing increases flight time and overestimates the jump. Contact mats and force plates are more reliable than phone apps.