Vertical Jump Power Calculator

How the Vertical Jump Power Calculator works

A vertical jump is a power event: the jumper accelerates their own body mass upward in a fraction of a second, and jump height records the outcome. This calculator converts that outcome back into an estimate of mechanical power output. It takes two inputs—jump height in centimetres and body mass in kilograms—and runs them through three published equations at once: the Sayers equation and the Harman equation, both of which estimate peak power, and the Lewis formula, which estimates average power over the propulsive phase. The Sayers value is shown as the headline result; all three appear in the detail rows.

The three equations

Sayers: P = 60.7 × jump (cm) + 45.3 × mass (kg) − 2055. Harman: P = 61.9 × jump (cm) + 36.0 × mass (kg) + 1822. Lewis: P = √4.9 × mass (kg) × √jump (m) × 9.81. For a jumper at 80 kg with a 50 cm jump, Sayers gives 60.7 × 50 + 45.3 × 80 − 2055 = 3,035 + 3,624 − 2,055 = 4,604 W. Harman gives 61.9 × 50 + 36.0 × 80 + 1,822 = 7,797 W. Lewis gives 2.2136 × 80 × 0.7071 × 9.81 ≈ 1,228 W. Three published equations, three different watt figures, from the same jump.

A second scenario

Take a heavier, more explosive athlete: 90 kg with a 70 cm jump. Sayers returns 60.7 × 70 + 45.3 × 90 − 2,055 = 4,249 + 4,077 − 2,055 = 6,271 W. Harman returns 61.9 × 70 + 36.0 × 90 + 1,822 = 9,395 W. Lewis returns 2.2136 × 90 × √0.70 × 9.81 ≈ 1,635 W. Note what happened between the two scenarios: mass rose 12.5% and jump height rose 40%, and every equation responded more strongly to the jump-height change than to the mass change—jump height carries the larger coefficient in both regression equations.

Why the three disagree

The largest gap is definitional. Sayers and Harman estimate peak power—the highest instantaneous power reached during the push-off—while Lewis estimates average power across the propulsive phase. Peak power during a countermovement jump is typically two to four times average power, so the Lewis number is not wrong so much as answering a different question. The remaining disagreement, between Sayers and Harman, comes from the samples and protocols behind each regression. The Harman equation was derived from a small sample of adult men; the Sayers equation was developed and cross-validated on a larger group of college-age athletes using force-platform data, and the 1999 paper reporting it found the earlier equations misestimated peak power in that population. Different samples produce different slopes and intercepts (−2,055 versus +1,822), so the two lines cross and diverge across the input range.

Band edges and measurement protocol

The Sayers equation has a large negative intercept, so very low combinations of jump height and body mass can push the arithmetic to zero or below—at 10 cm and 30 kg the equation returns −89 W. The calculator rejects such combinations rather than displaying a negative wattage, because they fall outside the population the regression was built on. Measurement protocol matters at the other end too: jump-and-reach tests, contact mats, and force platforms can differ by several centimetres for the same jump, and each centimetre moves the Sayers estimate by 60.7 W. Comparisons across athletes are most meaningful when every jump is measured the same way.

Combine-test context

Vertical jump testing is a fixture of athlete combines and field testing precisely because it requires no laboratory equipment, and power equations exist to translate the raw centimetre score into a mass-adjusted figure. Two athletes can jump the same 60 cm, but if one carries 25 kg more body mass, that athlete produced substantially more power to get there—the Sayers equation credits 45.3 W per additional kilogram. Regression estimates such as these are commonly used where force platforms are unavailable, with the understanding that they are population-level approximations of a quantity that only direct force measurement captures exactly.

What this tool does not do

This calculator does not measure power directly, prescribe plyometric or strength training, estimate rate of force development, or convert between countermovement and squat-jump scores. It does not model arm-swing contribution, drop-jump reactive strength, or fatigue across repeated jumps. The output is the result of three published regression equations applied to two numbers, and individual force-platform values can differ from any of the three estimates.

Disclaimer

This tool is intended for educational and informational purposes only. It is not medical, clinical, or training advice and does not replace consultation with a physician, physiotherapist, or certified coach. All calculations return population-derived estimates that may differ from individually measured values. Maximal-effort jumping carries inherent physical risk; users are responsible for their own testing decisions, technique, and supervision.