{
  "slug": "percentage",
  "title": "Percentage Calculator",
  "heading": "Percentage Calculator",
  "category": "math",
  "url": "https://www.revenuelab.fyi/toolbox/percentage",
  "summary": "What is X% of Y, what % is X of Y, and percent change.",
  "description": "Three common percentage operations in one place — handy for tips, discounts, growth rates, and quick math.",
  "formula": null,
  "dateModified": "2026-10-03",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=percentage",
  "inputs": [
    {
      "id": "x",
      "label": "X",
      "kind": "number",
      "hint": null,
      "default": 25,
      "unit": null,
      "min": null,
      "max": null
    },
    {
      "id": "y",
      "label": "Y",
      "kind": "number",
      "hint": null,
      "default": 200,
      "unit": null,
      "min": null,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "ofY",
      "label": "X% of Y",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "xPercentY",
      "label": "X is what % of Y",
      "format": "percent",
      "hint": null,
      "primary": false
    },
    {
      "id": "change",
      "label": "% change from X to Y",
      "format": "percent",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "X: 25",
      "Y: 200"
    ],
    "outputs": [
      "X% of Y: 50",
      "X is what % of Y: 12.50%",
      "% change from X to Y: 700.00%"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter x.",
      "Enter y.",
      "Read your x% of y 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": {
        "x": 15,
        "y": 120
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "x": 25,
        "y": 200
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "x": 40,
        "y": 320
      }
    }
  ],
  "limitations": [
    "Results are rounded for display; the underlying calculation keeps full precision.",
    "Very large or very small inputs may hit floating-point limits in the browser.",
    "Inputs outside the accepted range are clamped rather than rejected."
  ],
  "faq": [
    {
      "q": "How does the percentage calculator work?",
      "a": "Three common percentage operations in one place — handy for tips, discounts, growth rates, and quick math."
    },
    {
      "q": "What do I need to enter?",
      "a": "2 values: x, and y. 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 x% of y 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. Results are rounded for display; the underlying calculation keeps full precision."
    },
    {
      "q": "Who is this tool for?",
      "a": "It's built for students, developers, and anyone who needs the answer right now without setting up a spreadsheet."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/fraction",
    "https://www.revenuelab.fyi/toolbox/tip"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Percentage Calculator (https://www.revenuelab.fyi/toolbox/percentage)"
}