{
    "name": "Cycling Power to Weight Calculator",
    "url": "https://calculators.geekmidst.com/calculators/cycling-power-to-weight-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/cycling-power-to-weight-calculator.md",
    "category": "Health & fitness",
    "description": "Work out your cycling power-to-weight ratio in W/kg and W/lb, and the power or body weight needed to reach a target W/kg.",
    "summary": "Power-to-weight is your sustained power in watts divided by your body weight in kilograms. It is the number that matters most when the road goes uphill.",
    "also_called": [
        "Watts per kilo calculator",
        "W/kg 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": "power",
            "label": "Power",
            "type": "number",
            "default": "250",
            "unit": "W"
        },
        {
            "name": "weight",
            "label": "Body weight",
            "type": "number",
            "default": "70"
        },
        {
            "name": "weight_unit",
            "label": "Weight in",
            "type": "segmented",
            "default": "kg",
            "options": {
                "kg": "kg",
                "lb": "lb"
            }
        },
        {
            "name": "target",
            "label": "Target power-to-weight",
            "type": "number",
            "default": "4",
            "unit": "W/kg"
        }
    ],
    "outputs": [
        {
            "key": "wkg",
            "label": "Power-to-weight",
            "format": "number"
        },
        {
            "key": "w_per_lb",
            "label": "Watts per pound",
            "format": "number"
        },
        {
            "key": "power_for_target",
            "label": "Power needed for the target at this weight",
            "format": "integer"
        },
        {
            "key": "weight_for_target",
            "label": "Weight for the target at this power (in your unit)",
            "format": "number"
        }
    ],
    "formula": {
        "text": "W/kg = Power ÷ Body mass (kg);  Power for target = Target × Mass;  Mass for target = Power ÷ Target",
        "variables": {
            "Power": "sustained output in watts",
            "Mass": "rider body mass (1 lb = 0.45359237 kg)"
        }
    },
    "worked_example": {
        "inputs": {
            "power": "250",
            "weight": "70",
            "weight_unit": "kg",
            "target": "4"
        },
        "steps": [
            "250 W ÷ 70 kg = 3.57 W/kg.",
            "4 W/kg at 70 kg needs 4 × 70 = 280 W.",
            "At 250 W, 4 W/kg would mean 250 ÷ 4 = 62.5 kg."
        ],
        "result": "A 70 kg rider holding 250 W produces 3.57 W/kg; reaching 4 W/kg takes another 30 W."
    },
    "interpretation": "W/kg compares riders of different sizes on climbs. On flat roads absolute watts and aerodynamics matter more, so a heavier rider with lower W/kg can still be faster.",
    "assumptions": [
        "Body weight only; the bike’s weight is not included.",
        "Power is a sustained figure from the same kind of test each time."
    ],
    "limitations": [
        "Losing weight to raise W/kg can also cost power; any weight-loss plan should be discussed with a qualified professional."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Should I include the bike in the weight?",
            "answer": "Convention is body weight only. Total system weight matters for climbing-speed estimates, which need a separate physics model."
        },
        {
            "question": "Which power figure should I use?",
            "answer": "Use the same duration each time, for example your FTP or best 20-minute power, so that comparisons are fair."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Cycling Cadence to Speed Calculator",
            "url": "https://calculators.geekmidst.com/calculators/cycling-cadence-to-speed-calculator"
        },
        {
            "name": "BMI Calculator",
            "url": "https://calculators.geekmidst.com/calculators/bmi-calculator"
        },
        {
            "name": "Calories Burned Calculator",
            "url": "https://calculators.geekmidst.com/calculators/calories-burned-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}