Vertical Jump Power Calculator: Sayers & Lewis

Turn your jump height into watts: peak power from the Sayers equation, average power from the classic Lewis formula.

  • 2 cited sources
  • Calculates in your browser

Jump-and-reach: best of three.

Your answer

Appears here as you enter your details. No demo figures — the number is yours, or it is nothing.

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Methodology

Two published equations convert a jump-and-reach score and body mass into mechanical power:

  • Sayers squat-jump equation (peak power, watts): 60.7 × jump (cm) + 45.3 × mass (kg) − 2055. Sayers and colleagues derived this on 108 athletes and non-athletes against force-platform measurements, cross-validating the older equations in the process, it's the equation their paper recommends.
  • Lewis formula (average power, watts): √4.9 × mass (kg) × √jump (m) × 9.81. The historical standard, estimating average power over the propulsive phase from projectile mechanics.

Peak power is always substantially higher than average power, they are different physical quantities, which is why both numbers appear.

Interpreting your result

Power rewards both jump height and body mass: a 100 kg athlete jumping 45 cm produces far more absolute power than a 60 kg athlete jumping the same height. That's exactly why coaches estimate power rather than ranking raw jump heights when comparing athletes of different sizes.

For tracking your own training, test under identical conditions, same warm-up, same jump style (countermovement or squat jump), best of three attempts.

Limitations

  • The equations were derived from the vertical jump-and-reach test; jump heights from force plates or phone apps measure slightly different things and shift the estimate.
  • The Sayers equation was built on squat jumps (no countermovement); applying it to countermovement jumps stretches it slightly.
  • Estimates, not force-platform measurements, good for tracking and comparison, not for research.

Sources

Pull the receipts, 2 cited sources

FitTools · sources

  1. 01 Sayers SP, et al. Cross-validation of three jump power equations. Med Sci Sports Exerc 1999;31:572-577
  2. 02 Full text of the Sayers 1999 cross-validation study (MSSE)

Every formula cited ✓

Frequently asked questions

How do I measure my vertical jump?
The jump-and-reach method: mark your standing reach against a wall, then jump and mark the highest point you touch, the difference is your jump height. Take the best of three attempts, fully warmed up.
What's the difference between peak and average power?
Peak power is the highest instantaneous output during the jump (the Sayers estimate); average power is the mean over the whole propulsive phase (the Lewis estimate). Peak is always substantially larger, they are different quantities, not competing answers.
What is a good vertical jump?
Recreational adults commonly jump 30 to 50 cm; well-trained athletes in jumping sports commonly exceed 60 cm, and elite jumpers 75 cm+. Power output also rewards body mass, a heavier athlete produces more watts at the same jump height.
Why estimate power instead of just tracking jump height?
Jump height alone penalises heavier athletes. Converting to watts with body mass in the equation lets you compare athletes fairly and track whether force production is improving even while body weight changes.

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