{
  "slug": "bmi",
  "title": "BMI Calculator",
  "heading": "BMI Calculator",
  "category": "fitness-health",
  "url": "https://www.revenuelab.fyi/toolbox/bmi",
  "summary": "Calculate your Body Mass Index from height and weight.",
  "description": "BMI is weight in kilograms divided by height in meters squared. Under 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese.",
  "formula": "BMI = kg / m².",
  "dateModified": "2026-10-03",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=bmi",
  "inputs": [
    {
      "id": "units",
      "label": "Units",
      "kind": "select",
      "hint": null,
      "default": "imperial",
      "options": [
        {
          "value": "metric",
          "label": "Metric (kg, cm)"
        },
        {
          "value": "imperial",
          "label": "Imperial (lb, in)"
        }
      ]
    },
    {
      "id": "weight",
      "label": "Weight",
      "kind": "number",
      "hint": null,
      "default": 170,
      "unit": null,
      "min": 0,
      "max": null
    },
    {
      "id": "height",
      "label": "Height",
      "kind": "number",
      "hint": null,
      "default": 68,
      "unit": null,
      "min": 0,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "bmi",
      "label": "Your BMI",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "category",
      "label": "Category",
      "format": "raw",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Units: Imperial (lb, in)",
      "Weight: 170",
      "Height: 68"
    ],
    "outputs": [
      "Your BMI: 25.8",
      "Category: Overweight"
    ]
  },
  "how_to": {
    "title": "How to read your BMI",
    "steps": [
      "Pick Metric or Imperial — your scale and tape measure decide.",
      "Type your weight (lb or kg) and height (in or cm).",
      "Watch the BMI number and category update live as you adjust.",
      "If you're muscular, also check the Body Fat calculator — BMI overcounts lean mass."
    ]
  },
  "scenarios": [
    {
      "name": "5'10\" · 165 lb",
      "description": "Average-build adult.",
      "values": {
        "units": "imperial",
        "weight": 165,
        "height": 70
      }
    },
    {
      "name": "5'6\" · 140 lb",
      "description": "Petite frame.",
      "values": {
        "units": "imperial",
        "weight": 140,
        "height": 66
      }
    },
    {
      "name": "6'2\" · 220 lb",
      "description": "Taller, heavier build.",
      "values": {
        "units": "imperial",
        "weight": 220,
        "height": 74
      }
    },
    {
      "name": "Metric · 80 kg · 180 cm",
      "description": "Default metric setup.",
      "values": {
        "units": "metric",
        "weight": 80,
        "height": 180
      }
    }
  ],
  "limitations": [
    "Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.",
    "Results do not account for medical conditions, medication, or pregnancy.",
    "Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it."
  ],
  "faq": [
    {
      "q": "How does the bmi calculator work?",
      "a": "BMI is weight in kilograms divided by height in meters squared. Under 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese. The underlying maths is: BMI = kg / m²."
    },
    {
      "q": "What do I need to enter?",
      "a": "3 values: units, weight, and height. Each field starts with a sensible default, so you can change one number at a time and watch the result move."
    },
    {
      "q": "What does the your bmi result mean?",
      "a": "It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds."
    },
    {
      "q": "Is this calculator free, and do I need an account?",
      "a": "Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser."
    },
    {
      "q": "How accurate is the result?",
      "a": "It applies the standard formula exactly, so the arithmetic is precise. Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass."
    },
    {
      "q": "Who is this tool for?",
      "a": "It's built for anyone tracking a health or training target and wanting the standard formula applied correctly, without a signup or an app."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/bmr",
    "https://www.revenuelab.fyi/toolbox/tdee",
    "https://www.revenuelab.fyi/toolbox/calorie"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — BMI Calculator (https://www.revenuelab.fyi/toolbox/bmi)"
}