{
    "name": "Target Heart Rate Calculator",
    "url": "https://calculators.geekmidst.com/calculators/target-heart-rate-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/target-heart-rate-calculator.md",
    "category": "Health & fitness",
    "description": "Find your exercise heart-rate range with the Karvonen (heart-rate reserve) method or percentage of maximum, using Tanaka, 220 − age or a measured maximum.",
    "summary": "A target heart rate turns a training intensity, such as 50–85%, into beats per minute. The Karvonen method uses your resting heart rate, so it adjusts for fitness.",
    "also_called": [
        "Heart rate zone calculator",
        "Karvonen calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "age",
            "label": "Age",
            "type": "number",
            "default": "40",
            "unit": "years"
        },
        {
            "name": "max_formula",
            "label": "Maximum heart rate from",
            "type": "select",
            "default": "tanaka",
            "options": {
                "tanaka": "Tanaka: 208 − 0.7 × age",
                "fox": "Traditional: 220 − age",
                "measured": "My measured maximum"
            }
        },
        {
            "name": "max_hr",
            "label": "Measured maximum heart rate",
            "type": "number",
            "default": "180",
            "unit": "bpm",
            "shown_when": {
                "max_formula": "measured"
            }
        },
        {
            "name": "method",
            "label": "Method",
            "type": "segmented",
            "default": "karvonen",
            "options": {
                "karvonen": "Karvonen (reserve)",
                "percent_max": "% of maximum"
            }
        },
        {
            "name": "resting_hr",
            "label": "Resting heart rate",
            "type": "number",
            "default": "60",
            "unit": "bpm",
            "shown_when": {
                "method": "karvonen"
            }
        },
        {
            "name": "low_pct",
            "label": "Lower intensity",
            "type": "number",
            "default": "50",
            "unit": "%"
        },
        {
            "name": "high_pct",
            "label": "Upper intensity",
            "type": "number",
            "default": "85",
            "unit": "%"
        }
    ],
    "outputs": [
        {
            "key": "target_range",
            "label": "Target heart rate",
            "format": "text"
        },
        {
            "key": "target_low",
            "label": "Lower limit",
            "format": "integer"
        },
        {
            "key": "target_high",
            "label": "Upper limit",
            "format": "integer"
        },
        {
            "key": "max_hr",
            "label": "Maximum heart rate used",
            "format": "integer"
        },
        {
            "key": "reserve",
            "label": "Heart-rate reserve (Karvonen only)",
            "format": "integer"
        }
    ],
    "formula": {
        "text": "Karvonen: THR = HRrest + (HRmax − HRrest) × intensity;  % of max: THR = HRmax × intensity;  HRmax (Tanaka) = 208 − 0.7 × age",
        "variables": {
            "HRmax": "maximum heart rate, estimated from age or measured",
            "HRrest": "resting heart rate",
            "HRmax − HRrest": "heart-rate reserve",
            "intensity": "the training intensity as a fraction"
        }
    },
    "worked_example": {
        "inputs": {
            "age": "40",
            "max_formula": "tanaka",
            "max_hr": "180",
            "method": "karvonen",
            "resting_hr": "60",
            "low_pct": "50",
            "high_pct": "85"
        },
        "steps": [
            "HRmax = 208 − 0.7 × 40 = 180 bpm.",
            "Reserve = 180 − 60 = 120 bpm.",
            "Lower: 60 + 120 × 0.50 = 120 bpm; upper: 60 + 120 × 0.85 = 162 bpm."
        ],
        "result": "A 40-year-old with a resting pulse of 60 would train between about 120 and 162 beats per minute at 50–85% intensity."
    },
    "interpretation": "The lower half of the range suits easy, longer sessions; the upper half suits harder intervals. If a measured maximum from a supervised test is available, use it: age formulas can be off by 10 bpm or more for an individual.",
    "assumptions": [
        "You are a healthy adult without heart conditions or heart-rate-limiting medicines such as beta-blockers.",
        "Maximum heart rate follows the chosen age formula unless you enter a measured value."
    ],
    "limitations": [
        "Tanaka et al. (2001) found a standard deviation of roughly 10 bpm around the age prediction.",
        "220 − age overestimates maximum heart rate in young adults and underestimates it in older adults.",
        "Heat, dehydration, caffeine and fatigue all change heart rate at a given effort."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Karvonen or percentage of max?",
            "answer": "Karvonen accounts for resting heart rate, so two people of the same age but different fitness get different targets. Percentage of max is simpler and needs no resting measurement; at the same percentage it gives lower numbers."
        },
        {
            "question": "Is there a special “fat-burning zone”?",
            "answer": "At lower intensities a larger share of the energy comes from fat, but total energy used per minute is lower. For body-fat change, total weekly activity and diet matter more than the zone."
        },
        {
            "question": "Should I check with a doctor first?",
            "answer": "Yes, if you have heart, lung or metabolic disease, symptoms on exertion, or take medication that affects heart rate."
        }
    ],
    "sources": [
        {
            "title": "Tanaka, Monahan & Seals (2001): Age-predicted maximal heart rate revisited",
            "url": "https://webs.um.es/jlyuste/documts/tanaka.pdf"
        }
    ],
    "related": [
        {
            "name": "One Rep Max Calculator",
            "url": "https://calculators.geekmidst.com/calculators/one-rep-max-calculator"
        },
        {
            "name": "TDEE Calculator",
            "url": "https://calculators.geekmidst.com/calculators/tdee-calculator"
        },
        {
            "name": "BMR Calculator",
            "url": "https://calculators.geekmidst.com/calculators/bmr-calculator"
        },
        {
            "name": "Age Calculator",
            "url": "https://calculators.geekmidst.com/calculators/age-calculator"
        }
    ],
    "disclaimer": "This is a general screening estimate for adults, not medical advice or a diagnosis. Talk to a qualified health professional about your health.",
    "publisher": "GM¹X CalcVerse"
}