{
  "slug": "macro",
  "title": "Macro Calculator",
  "heading": "Macronutrient Calculator",
  "category": "fitness-health",
  "url": "https://www.revenuelab.fyi/toolbox/macro",
  "summary": "Split daily calories into protein, carbs, and fat.",
  "description": "Translate a target calorie number into grams of protein, carbs, and fat using a chosen split.",
  "formula": "Protein/Carbs use 4 kcal/g; fat uses 9 kcal/g.",
  "dateModified": "2026-10-03",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=macro",
  "inputs": [
    {
      "id": "calories",
      "label": "Daily calories",
      "kind": "number",
      "hint": null,
      "default": 2200,
      "unit": "kcal",
      "min": 0,
      "max": null
    },
    {
      "id": "protein",
      "label": "Protein",
      "kind": "number",
      "hint": null,
      "default": 30,
      "unit": "%",
      "min": 0,
      "max": 100
    },
    {
      "id": "carbs",
      "label": "Carbs",
      "kind": "number",
      "hint": null,
      "default": 40,
      "unit": "%",
      "min": 0,
      "max": 100
    },
    {
      "id": "fat",
      "label": "Fat",
      "kind": "number",
      "hint": null,
      "default": 30,
      "unit": "%",
      "min": 0,
      "max": 100
    }
  ],
  "outputs": [
    {
      "id": "proteinG",
      "label": "Protein (g)",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "carbsG",
      "label": "Carbs (g)",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "fatG",
      "label": "Fat (g)",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "total",
      "label": "Split total (should be 100)",
      "format": "number",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Daily calories: 2200 kcal",
      "Protein: 30 %",
      "Carbs: 40 %",
      "Fat: 30 %"
    ],
    "outputs": [
      "Protein (g): 165",
      "Carbs (g): 220",
      "Fat (g): 73",
      "Split total (should be 100): 100"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter daily calories (kcal).",
      "Enter protein (%).",
      "Enter carbs (%).",
      "Enter fat (%).",
      "Read your protein (g) on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "calories": 1320,
        "protein": 18,
        "carbs": 24,
        "fat": 18
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "calories": 2200,
        "protein": 30,
        "carbs": 40,
        "fat": 30
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "calories": 3520,
        "protein": 48,
        "carbs": 64,
        "fat": 48
      }
    }
  ],
  "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 macronutrient calculator work?",
      "a": "Translate a target calorie number into grams of protein, carbs, and fat using a chosen split. The underlying maths is: Protein/Carbs use 4 kcal/g; fat uses 9 kcal/g."
    },
    {
      "q": "What do I need to enter?",
      "a": "4 values: daily calories, protein, carbs, and fat. 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 protein (g) 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/calorie",
    "https://www.revenuelab.fyi/toolbox/tdee",
    "https://www.revenuelab.fyi/toolbox/bmr"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Macro Calculator (https://www.revenuelab.fyi/toolbox/macro)"
}