{
  "slug": "ftp-calculator",
  "title": "FTP Calculator (from 20-Min Test)",
  "category": "Cycling",
  "category_slug": "cycling",
  "tier": 1,
  "summary": "Estimate Functional Threshold Power by applying a 0.95 factor to your 20-minute test result.",
  "description": "This calculator estimates Functional Threshold Power (FTP) by applying the standard 0.95 conversion factor to a 20-minute maximal cycling test, following the protocol introduced by Andrew Coggan and Hunter Allen. It takes a single input—average power sustained during a 20-minute all-out effort—and returns estimated FTP in watts, representing the power output an athlete can theoretically sustain for one hour. The 5% reduction accounts for the typical difference in fatigue accumulation between 20-minute and 60-minute maximal efforts, making this a widely adopted field-test alternative to a full one-hour FTP test.",
  "page_url": "https://fitmetriclab.com/en/tools/cycling/ftp-calculator/",
  "api_url": "https://fitmetriclab.com/api/tools/ftp-calculator.json",
  "formula": {
    "id": "ftp_calculator",
    "expression": "\\text{FTP} = 0.95 \\times P_{20}",
    "variables": [
      {
        "symbol": "P_{20}",
        "description": "Best 20-minute average power in watts"
      }
    ]
  },
  "inputs": [
    {
      "id": "twenty_min_power",
      "label": "20-Min Power",
      "type": "number",
      "unit": "W",
      "default": 260,
      "min": 50,
      "max": 700,
      "step": 1
    }
  ],
  "worked_example": {
    "inputs": {
      "twenty_min_power": 260
    },
    "expected_output": "247 W"
  },
  "result_summary_template": "For a 20-minute all-out test producing {twenty_min_power}, the 0.95 conversion factor estimates FTP at {result}.",
  "methodology": "FTP = 20-minute average power × 0.95. This conversion factor, introduced by Andrew Coggan and Hunter Allen, estimates one-hour sustainable power from a shorter maximal test. The 0.95 multiplier reflects typical fatigue accumulation differences between 20-minute and 60-minute efforts.",
  "sources": [
    {
      "label": "Allen H, Coggan A. Training and Racing with a Power Meter. VeloPress. 2010.",
      "url": "https://www.velopress.com/"
    },
    {
      "label": "Coggan AR. Training and racing using a power meter: an introduction. USA Cycling. 2003.",
      "url": "https://www.usacycling.org/"
    },
    {
      "label": "Pinot J, Grappe F. The record power profile to assess performance in elite cyclists. Int J Sports Med. 2011;32(11):839-844.",
      "url": "https://pubmed.ncbi.nlm.nih.gov/22052022/"
    }
  ],
  "faqs": [
    {
      "question": "Why multiply by 0.95 instead of using the 20-minute power directly?",
      "answer": "A maximal 20-minute effort typically produces slightly higher power than an athlete can sustain for a full hour. The 0.95 factor estimates the power sustainable at lactate threshold over 60 minutes by accounting for the shorter test duration and pacing strategy."
    },
    {
      "question": "Does the 0.95 multiplier work for everyone?",
      "answer": "Individual physiology varies. Some cyclists find their true hour power closer to 93% or 97% of their 20-minute best. The 0.95 value represents a population average and serves as a starting point for structured training, often refined through additional testing or real-world validation."
    },
    {
      "question": "How often can a 20-minute FTP test be performed?",
      "answer": "Testing frequency depends on training phase and recovery capacity. Many cyclists retest every 6–12 weeks to track fitness changes, allowing adequate recovery and adaptation between assessments. More frequent testing may interfere with training adaptation."
    },
    {
      "question": "What conditions affect the accuracy of a 20-minute test?",
      "answer": "Wind, gradient, temperature, altitude, and recent training stress all influence power output. Controlled indoor trainer tests minimize environmental variables, while outdoor tests require consistent routes and weather. Fatigue from prior workouts or inadequate warm-up also impacts results."
    },
    {
      "question": "Can this FTP estimate be used to set training zones?",
      "answer": "Many training frameworks define zones as percentages of FTP. The estimate from this calculator provides a reference point; athletes often adjust zones based on perceived exertion, heart rate, and performance in key workouts. Individual responses to intensity vary."
    }
  ],
  "related_tools": [
    {
      "slug": "cycling-power",
      "title": "Cycling Power Calculator (Watts from Speed)",
      "api_url": "https://fitmetriclab.com/api/tools/cycling-power.json",
      "page_url": "https://fitmetriclab.com/en/tools/cycling/cycling-power/"
    },
    {
      "slug": "cycling-power-zones",
      "title": "Cycling Power Zones Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/cycling-power-zones.json",
      "page_url": "https://fitmetriclab.com/en/tools/cycling/cycling-power-zones/"
    },
    {
      "slug": "chain-length",
      "title": "Chain Length Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/chain-length.json",
      "page_url": "https://fitmetriclab.com/en/tools/cycling/chain-length/"
    }
  ],
  "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."
}