{
  "slug": "running-power",
  "title": "Running Power Calculator",
  "category": "Running",
  "category_slug": "running",
  "tier": 3,
  "summary": "Estimate running power in watts from body weight and pace using a Stryd-style metabolic coefficient.",
  "description": "This calculator estimates running power in watts using a Stryd-style metabolic coefficient applied to body weight and running pace. It converts pace to speed in metres per second, then multiplies by body weight and a coefficient of 1.04 W/(kg·m/s) to produce an estimated power output. The result represents a population-average approximation of the mechanical and metabolic power required for flat-ground running at moderate paces, not a direct measurement from a wearable device.",
  "page_url": "https://fitmetriclab.com/en/tools/running/running-power/",
  "api_url": "https://fitmetriclab.com/api/tools/running-power.json",
  "formula": {
    "id": "running_power",
    "expression": "v_{m/s} = \\frac{1000}{p_{sec/km}}, \\quad P_{W} = w_{kg} \\times v_{m/s} \\times 1.04",
    "variables": [
      {
        "symbol": "w",
        "description": "Weight in kg"
      },
      {
        "symbol": "p",
        "description": "Pace in sec/km"
      }
    ]
  },
  "inputs": [
    {
      "id": "weight_kg",
      "label": "Weight",
      "type": "number",
      "unit": "kg",
      "default": 75,
      "min": 20,
      "max": 300,
      "step": 0.1
    },
    {
      "id": "pace_sec_per_km",
      "label": "Pace",
      "type": "number",
      "unit": "s/km",
      "default": 300,
      "min": 120,
      "max": 900,
      "step": 1
    }
  ],
  "worked_example": {
    "inputs": {
      "weight_kg": 75,
      "pace_sec_per_km": 300
    },
    "expected_output": "260 W"
  },
  "result_summary_template": "For a runner weighing {weight_kg} kg at a pace of {pace_sec_per_km} seconds per kilometre, the estimated running power is {result}.",
  "methodology": "Speed (m/s) = 1000 ÷ pace_sec_per_km. Power (W) = weight_kg × speed_m/s × 1.04, where 1.04 W/(kg·m/s) is a metabolic-power-to-velocity coefficient derived from Stryd's flat-ground running-power model for moderate paces.",
  "sources": [
    {
      "label": "Minetti AE, Moia C, Roi GS, et al. Energy cost of walking and running at extreme uphill and downhill slopes. J Appl Physiol. 2002;93(3):1039–1046.",
      "url": "https://pubmed.ncbi.nlm.nih.gov/12183501/"
    },
    {
      "label": "di Prampero PE, Atchou G, Brückner JC, Moia C. The energetics of endurance running. Eur J Appl Physiol Occup Physiol. 1986;55(3):259–266.",
      "url": "https://pubmed.ncbi.nlm.nih.gov/3732247/"
    },
    {
      "label": "Stryd Power Meter: Scientific Basis (white paper). Stryd, Inc. 2016.",
      "url": "https://blog.stryd.com/2016/11/07/the-science-behind-stryd-power-for-running/"
    }
  ],
  "faqs": [
    {
      "question": "How accurate is this power estimate compared to a Stryd pod?",
      "answer": "The calculator uses a population-average coefficient and ignores individual running economy, form efficiency, ground contact time, and environmental factors. Real Stryd readings can differ by 10–20% depending on biomechanics, grade, and wind. This tool provides a ballpark figure for flat-ground running at moderate paces."
    },
    {
      "question": "Why does the formula use 1.04 W/(kg·m/s)?",
      "answer": "The coefficient 1.04 represents the average metabolic cost of level running at moderate speeds, consistent with research-backed models used by Stryd. At 3–4 m/s, most runners expend approximately 1 watt per kilogram body mass per metre per second sustained, though individual variation exists."
    },
    {
      "question": "Can I use this to set training zones?",
      "answer": "This calculator provides an estimate, not a prescription. Training zones depend on individual lactate threshold, VO₂max, running economy, and periodization goals. Calibrated power-meter data combined with field testing and coaching input offer a more reliable foundation for zone design."
    },
    {
      "question": "Does the calculator account for hills or wind?",
      "answer": "No. The formula assumes flat ground with no wind resistance. Running uphill or into a headwind increases actual power demand significantly. For grade-adjusted power, hardware sensors with accelerometers and barometric altimeters are necessary."
    },
    {
      "question": "How does running power differ from cycling power?",
      "answer": "Cycling power is direct mechanical work measured at the crank or hub. Running power models metabolic cost because the foot applies force to the ground in a complex, elastic manner. Running power values are typically lower than cycling power at similar heart rates due to differences in muscle recruitment and movement efficiency."
    }
  ],
  "related_tools": [
    {
      "slug": "age-graded-performance",
      "title": "Age-Graded Running Performance Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/age-graded-performance.json",
      "page_url": "https://fitmetriclab.com/en/tools/running/age-graded-performance/"
    },
    {
      "slug": "running-cadence",
      "title": "Running Cadence Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/running-cadence.json",
      "page_url": "https://fitmetriclab.com/en/tools/running/running-cadence/"
    },
    {
      "slug": "running-pace",
      "title": "Running Pace Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/running-pace.json",
      "page_url": "https://fitmetriclab.com/en/tools/running/running-pace/"
    }
  ],
  "last_updated": "2026-04-22",
  "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."
}