{
  "slug": "vertical-jump-power",
  "title": "Vertical Jump Power Calculator",
  "category": "Strength Training",
  "category_slug": "strength-training",
  "tier": 2,
  "summary": "Convert a vertical jump into watts with the Sayers, Harman, and Lewis equations side by side.",
  "description": "This calculator estimates lower-body mechanical power from a vertical jump measurement and body mass, using three published equations displayed side by side: the Sayers equation (peak power), the Harman equation (peak power), and the Lewis formula (average power). It requires jump height in centimetres and body mass in kilograms, and returns each estimate in watts with the Sayers value as the headline figure. The equations were derived by regression against force-platform measurements and produce systematically different numbers, so the comparison shows the range of published estimates rather than a single answer.",
  "page_url": "https://fitmetriclab.com/en/tools/strength-training/vertical-jump-power/",
  "api_url": "https://fitmetriclab.com/api/tools/vertical-jump-power.json",
  "formula": {
    "id": "vertical_jump_power",
    "expression": "P_{\\text{peak}} = 60.7 \\times h_{cm} + 45.3 \\times m_{kg} - 2055",
    "variables": [
      {
        "symbol": "h_{cm}",
        "description": "Vertical jump height in cm"
      },
      {
        "symbol": "m_{kg}",
        "description": "Body mass in kg"
      }
    ]
  },
  "inputs": [
    {
      "id": "jump_cm",
      "label": "Vertical jump height",
      "type": "number",
      "unit": "cm",
      "default": 50,
      "min": 10,
      "max": 130,
      "step": 0.5
    },
    {
      "id": "weight_kg",
      "label": "Body mass",
      "type": "number",
      "unit": "kg",
      "default": 80,
      "min": 30,
      "max": 200,
      "step": 0.1
    }
  ],
  "worked_example": {
    "inputs": {
      "jump_cm": 50,
      "weight_kg": 80
    },
    "expected_output": "4,604 W"
  },
  "result_summary_template": "A vertical jump of {jump_cm} cm at a body mass of {weight_kg} kg corresponds to an estimated Sayers peak power of {result}.",
  "methodology": "Applies three published jump-power equations to jump height h (cm) and body mass m (kg). Sayers peak power = 60.7×h + 45.3×m − 2055 W. Harman peak power = 61.9×h + 36.0×m + 1822 W. Lewis average power = √4.9 × m × √(h in metres) × 9.81 W. The Sayers value is the primary result; all three are listed with a note distinguishing peak from average power. Combinations for which the Sayers regression returns a non-positive value are rejected as outside the validated range.",
  "sources": [
    {
      "label": "Sayers SP, Harackiewicz DV, Harman EA, Frykman PN, Rosenstein MT. Cross-validation of three jump power equations. Med Sci Sports Exerc. 1999;31(4):572–577.",
      "url": "https://pubmed.ncbi.nlm.nih.gov/10199785/"
    },
    {
      "label": "Harman EA, Rosenstein MT, Frykman PN, Rosenstein RM, Kraemer WJ. Estimation of human power output from vertical jump. J Appl Sport Sci Res. 1991;5(3):116–120.",
      "url": ""
    },
    {
      "label": "Fox EL, Mathews DK. The Physiological Basis of Physical Education and Athletics. Philadelphia, PA: Saunders College Publishing; 1981 (Lewis formula).",
      "url": ""
    }
  ],
  "faqs": [
    {
      "question": "Why is the Lewis value so much lower than the Sayers and Harman values?",
      "answer": "The Lewis formula estimates average power across the propulsive phase of the jump, derived from falling-body mechanics, while Sayers and Harman estimate peak instantaneous power from regression against force-platform data. Peak power during a countermovement jump typically runs two to four times average power, so a Lewis figure of roughly 1,200 W and a Sayers figure of roughly 4,600 W for the same jump are describing different quantities, not contradicting each other."
    },
    {
      "question": "Which equation is used as the headline result, and why?",
      "answer": "The calculator displays the Sayers estimate as the primary figure. The 1999 Sayers paper cross-validated earlier jump-power equations on a college-age athletic sample and reported that its own regression tracked force-platform peak power more closely in that population. That makes it the most commonly cited of the three in field-testing contexts, though all three values are shown so the spread between published estimates stays visible."
    },
    {
      "question": "Does it matter how the jump height was measured?",
      "answer": "Yes. Jump-and-reach tests, contact mats measuring flight time, and force platforms can disagree by several centimetres for the same jump, because each method makes different assumptions about take-off and landing position. Every centimetre of measurement difference shifts the Sayers estimate by 60.7 W and the Harman estimate by 61.9 W. Comparisons between athletes, or across time for one athlete, are most meaningful when the measurement method is held constant."
    },
    {
      "question": "Why does the calculator reject very low jump and body-mass combinations?",
      "answer": "The Sayers equation is a linear regression with an intercept of −2,055 W. For combinations far below the range of the sample it was built on—for example a 10 cm jump at 30 kg body mass—the arithmetic produces a negative wattage, which has no physical meaning. The calculator returns an error for such inputs rather than displaying a negative power, since they fall outside the equation's validated range."
    },
    {
      "question": "Can two athletes with the same jump height have different power outputs?",
      "answer": "Yes, and this is the main reason power equations exist alongside raw jump scores. Accelerating a heavier body to the same take-off velocity requires more force and therefore more power. The Sayers equation adds 45.3 W per kilogram of body mass at a given jump height, so a 100 kg athlete and a 75 kg athlete who both jump 60 cm receive estimates more than 1,100 W apart."
    }
  ],
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  "last_updated": "2026-08-08",
  "price": {
    "value": 0,
    "currency": "USD"
  },
  "runs_in_browser": true,
  "disclaimer": "Educational estimate produced from a published formula. Not medical, nutritional, or training advice. Calculations are deterministic — apply the formula to the inputs to reproduce the result."
}