{
  "id": "target-heart-rate",
  "version": "4ca84f4e8970",
  "status": "published",
  "name": "Target Heart Rate Calculator",
  "question": "What’s my target heart rate?",
  "summary": "Works out the CDC target heart rate zones for moderate (64% to 76%) and vigorous (77% to 93%) exercise from the age-predicted maximum heart rate, and where a measured heart rate falls.",
  "category": "health",
  "subcategory": "body",
  "url": "https://www.acalculator.org/health/target-heart-rate-calculator",
  "markdown": "https://www.acalculator.org/health/target-heart-rate-calculator.md",
  "kind": "function",
  "method": "Maximum heart rate = 220 − age (or 208 − 0.7 × age); moderate zone = 64% to 76% of the maximum; vigorous zone = 77% to 93% (CDC). A checked heart rate is light below 64%, moderate from 64% to under 77%, vigorous from 77% to under 100%.",
  "assumptions": [
    "The maximum heart rate is estimated from age alone; a person’s measured maximum can differ by 10 beats per minute or more.",
    "The zones are the CDC’s percentages of the maximum heart rate, taken from the ACSM exercise guidelines.",
    "A checked heart rate is light below 64% of the maximum, moderate from 64% to under 77%, and vigorous from 77% up to the maximum.",
    "This is for information only and is not medical advice. Heart-rate medicines such as beta blockers change the response to exercise."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "age": {
        "title": "Age",
        "description": "Your age in whole years.",
        "type": "integer",
        "minimum": 15,
        "maximum": 100
      },
      "intensity": {
        "title": "Exercise intensity",
        "description": "Moderate is 64% to 76% of the maximum heart rate; vigorous is 77% to 93% (CDC).",
        "type": "string",
        "enum": [
          "moderate",
          "vigorous"
        ]
      },
      "formula": {
        "title": "Maximum heart rate formula",
        "description": "How the maximum heart rate is estimated from age: 220 − age (CDC) or 208 − 0.7 × age (Tanaka).",
        "type": "string",
        "enum": [
          "fox",
          "tanaka"
        ]
      },
      "hr": {
        "title": "Heart rate to check",
        "description": "A heart rate measured during exercise, in beats per minute, to see which zone it is in.",
        "type": "integer",
        "minimum": 30,
        "maximum": 250
      }
    }
  },
  "outputs": {
    "zone": {
      "label": "Target heart rate",
      "description": "The target zone for the chosen intensity, in whole beats per minute.",
      "format": "text"
    },
    "low": {
      "label": "Zone starts at",
      "description": "The lower end of the chosen zone in beats per minute: the lower share × the maximum.",
      "format": "number"
    },
    "high": {
      "label": "Zone ends at",
      "description": "The upper end of the chosen zone in beats per minute: the upper share × the maximum.",
      "format": "number"
    },
    "max": {
      "label": "Estimated max heart rate",
      "description": "The age-predicted maximum heart rate in beats per minute.",
      "format": "number"
    },
    "pct": {
      "label": "Checked heart rate, % of max",
      "description": "The heart rate to check as a percent of the estimated maximum, with its intensity band.",
      "format": "percent"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "age": 50,
      "intensity": "moderate",
      "formula": "fox",
      "hr": 120
    },
    "outputs": {
      "zone": "109 to 129 bpm",
      "low": 108.8,
      "high": 129.2,
      "max": 170,
      "pct": 70.58823529411765
    },
    "text": "Moderate intensity at age 50: keep your heart rate at 109 to 129 bpm."
  },
  "examples": [
    {
      "given": {
        "age": 50,
        "intensity": "moderate",
        "formula": "fox"
      },
      "expect": {
        "max": 170,
        "low": 108.8,
        "high": 129.2,
        "zone": "109 to 129 bpm"
      },
      "source": "CDC, Target Heart Rate and Estimated Maximum Heart Rate: age 50, 170 × 0.64 = 109 bpm and 170 × 0.76 = 129 bpm"
    },
    {
      "given": {
        "age": 35,
        "intensity": "vigorous",
        "formula": "fox"
      },
      "expect": {
        "max": 185,
        "low": 142.45,
        "high": 172.05,
        "zone": "142 to 172 bpm"
      },
      "source": "CDC, Target Heart Rate and Estimated Maximum Heart Rate: age 35, 185 × 0.77 = 142 bpm and 185 × 0.93 = 172 bpm"
    },
    {
      "given": {
        "age": 40,
        "intensity": "moderate",
        "formula": "tanaka",
        "hr": 150
      },
      "expect": {
        "max": 180,
        "low": 115.2,
        "high": 136.8,
        "zone": "115 to 137 bpm",
        "pct": 83.33333333333334
      },
      "source": "hand calculation in content.mdx: Tanaka 2001, 208 − 0.7 × 40 = 180; CDC shares 0.64 and 0.76; 150 ÷ 180 = 83.3%, in the vigorous range"
    },
    {
      "given": {
        "age": 50,
        "intensity": "moderate",
        "formula": "fox",
        "hr": 120
      },
      "expect": {
        "pct": 70.58823529411765
      },
      "source": "hand calculation in content.mdx: 120 ÷ (220 − 50) = 70.6%, in the CDC moderate range (64% to 76%)"
    }
  ],
  "sources": [
    "Centers for Disease Control and Prevention, How to Measure Physical Activity Intensity (last reviewed December 4, 2025). https://www.cdc.gov/physical-activity-basics/measuring/index.html",
    "Centers for Disease Control and Prevention, Target Heart Rate and Estimated Maximum Heart Rate (last reviewed June 3, 2022; no longer on cdc.gov; archived copy). http://web.archive.org/web/20221225180518/https://www.cdc.gov/physicalactivity/basics/measuring/heartrate.htm",
    "Riebe D, Ehrman JK, Liguori G, Magal M. ACSM's Guidelines for Exercise Testing and Prescription, 10th edition, chapter 6. Wolters Kluwer, 2018 (the source of the CDC percentages).",
    "Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology 2001;37:153–156. doi:10.1016/s0735-1097(00)01054-8",
    "Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae 1957;35:307–315."
  ],
  "related": [
    "max-heart-rate",
    "calories-burned-walking"
  ],
  "changelog": [
    {
      "date": "2026-09-28",
      "note": "The checked-rate bands read “Checked rate: …”, so the chip is not taken for the chosen intensity."
    }
  ]
}