Last updated: 2026-06-21

Turning a Jump Into Watts

A vertical jump is one of the purest tests of lower-body explosiveness: how much power can you channel through your legs in a fraction of a second? A jump mat or force plate measures this directly, but you do not need one. Two well-known equations estimate leg power in watts from just your jump height and body mass — numbers anyone can collect with a wall and a tape measure.

This calculator implements both the Sayers peak-power equation and the older Lewis average-power formula, so you can read explosive output as a single trackable figure.

The Two Equations

Sayers (peak power)

The Sayers equation is a regression fitted to force-plate data and returns peak power in watts:

where $h_{cm}$ is jump height in centimetres and $m$ is body mass in kilograms. It is the modern default and the figure most strength reports quote.

Lewis (average power)

The Lewis formula predates force plates and comes straight from physics. It returns average power over the push-off:

with $h$ in metres and $g = 9.81 \ \text{m/s}^2$. Because it describes the average rather than the instantaneous peak, it returns a lower number than Sayers for the same jump.

Worked Example

An athlete with a 50 cm vertical jump weighing 75 kg:

Sayers peak power: $60.7 \times 50 + 45.3 \times 75 - 2055 = 4377.5$ W, about 4378 W. Lewis average power: $\sqrt{4.9} \times 75 \times \sqrt{0.5} \times 9.81 \approx 1152$ W. The peak figure is roughly four times the average — exactly what you expect, since peak captures the highest instant and average smooths over the whole take-off. A 50 cm jump is about 19.7 inches and a 75 kg athlete weighs roughly 165 lb. The equations are defined in metric units, so the inputs convert first: Sayers peak power works out to about 4378 W and Lewis average power to about 1152 W.

Measuring Your Jump

The cheapest reliable test is jump-and-reach. Mark your standing reach against a wall, then jump and touch the highest point you can with a chalked finger; the gap between the marks is your vertical jump. Use a counter-movement jump — a quick downward dip before exploding upward — and record the best of three maximal attempts with full recovery between them.

Building More Power

Explosive power grows fastest when heavy strength work and plyometrics run together. Squats and deadlifts raise the force your legs can produce; box jumps, depth jumps and repeated maximal jumps teach the nervous system to deliver that force quickly. Re-test every few weeks and watch the wattage climb.