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How to Estimate Leg Power From a Vertical Jump
Manesh Jayawardhana
CIO & Co-founder
Jump height is a good number. Power output is a better one, because it accounts for the fact that moving 95 kg to the same height as 70 kg is substantially more work.
The equations that convert one into the other are simple, well established, and extremely sensitive to how you measured the jump — which is where most people’s numbers go wrong.
What the equations do
Both estimate power from jump height and body mass, using coefficients fitted to test populations against force-plate measurements.
Sayers peak power, the more commonly used:
peak power (W) = 60.7 × jump height (cm) + 45.3 × body mass (kg) − 2055
A 54 cm jump at 78 kg gives about 4,495 watts.
Lewis average power estimates mean rather than peak output, using a different derivation based on flight time and mass.
They’re regression equations, not physics. They approximate what a force plate would measure, and there’s a genuine margin of error against direct measurement. That’s fine for tracking change over time; it’s less appropriate for comparing against published elite figures as though the numbers were exact.
The measurement problem
Jump height can be measured several ways and they don’t agree.
Reach-and-jump (a Vertec or chalk mark) measures the difference between standing reach and jump reach. It’s affected by arm extension and shoulder mobility as much as by leg power.
Flight time (a jump mat) calculates height from how long you’re airborne. It’s affected by whether you tuck your legs — landing with knees bent extends flight time and inflates the height.
Force plate measures directly and is the reference standard, and also the one nobody has.
The differences between methods are large enough that mixing them in one log makes the data meaningless. Pick one and never change it mid-programme.
| Method | Measures | Watch Out |
|---|---|---|
| Reach and jump | Displacement | Arm reach technique |
| Jump mat | Flight time | Tucking legs inflates height |
| Force plate | Force directly | Rarely available |
Why people get stuck here
- Mixing measurement methods. The most common cause of nonsense trends.
- Inconsistent technique. Countermovement depth, arm swing allowed or not — these change height substantially.
- Comparing against published norms. Which were collected using a specific method you probably didn’t use.
- Testing when fatigued. Power output is highly sensitive to fatigue, so test order within a session matters.
What good testing looks like
One method, one protocol
Same measurement device, same arm swing rule, same countermovement instruction, same warm-up. Write it down and follow it every time.
Fresh, early in the session
Power testing goes first, after warm-up and before anything fatiguing. A jump test at the end of a session measures fatigue as much as power.
Best of three, recorded with the others
Take the best jump but record all attempts. Falling attempts across three jumps tells you something about fatigue that the best figure alone hides.
Common mistakes to avoid
- Switching from a chalk mark to a jump mat and treating the trend as continuous.
- Allowing arm swing on some tests and not others.
- Testing after squats and comparing to a fresh-day figure.
- Reporting an estimated wattage as though it were measured.
- Comparing your figure to an athlete’s without knowing which method produced theirs.
How to do it with Vertical Jump Power Calculator
The Vertical Jump Power Calculator applies both equations and shows which is which.
- Measure jump height with a consistent method and note which one.
- Enter body mass in kilograms — power scales directly with it.
- Read peak and average power estimates together.
- Track the trend across sessions rather than comparing a single figure to published tables.
Other performance calculators are in the tools directory.
Frequently asked questions
Which measurement method should I use?
Whichever you can repeat exactly. A jump mat and a reach test give different heights for the same jump, so consistency matters more than which one you choose.
Is a higher jump always more power?
Not across people. A heavier athlete jumping slightly lower can be producing more power, which is exactly why mass appears in the equation.
How accurate are these estimates?
They’re regressions fitted to test populations, so expect a margin against force-plate measurement. Reliable for tracking change, less so as absolute values.
Final thought
Fix your protocol before your first test, not after the third. The equations are the easy part — the measurement is what determines whether the trend means anything.