{
  "slug": "logarithm",
  "title": "Logarithm Calculator",
  "heading": "Logarithm Calculator",
  "category": "math",
  "url": "https://www.revenuelab.fyi/toolbox/logarithm",
  "summary": "Log at any base, natural log, and log base 10.",
  "description": "A logarithm answers 'what power do I raise this base to?'. Logs at arbitrary bases are computed with the change-of-base rule.",
  "formula": "log_b(x) = ln(x) ÷ ln(b).",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=logarithm",
  "inputs": [
    {
      "id": "value",
      "label": "Value (x)",
      "kind": "number",
      "hint": null,
      "default": 1000,
      "unit": null,
      "min": 1e-7,
      "max": null
    },
    {
      "id": "base",
      "label": "Base (b)",
      "kind": "number",
      "hint": null,
      "default": 10,
      "unit": null,
      "min": 1e-7,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "result",
      "label": "log at your base",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "ln",
      "label": "Natural log (ln)",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "log10",
      "label": "Log base 10",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "log2",
      "label": "Log base 2",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Value (x): 1000",
      "Base (b): 10"
    ],
    "outputs": [
      "log at your base: 3",
      "Natural log (ln): 6.907755",
      "Log base 10: 3",
      "Log base 2: 9.965784"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter value (x).",
      "Enter base (b).",
      "Read your log at your base 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": {
        "value": 600,
        "base": 6
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "value": 1000,
        "base": 10
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "value": 1600,
        "base": 16
      }
    }
  ],
  "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 logarithm calculator work?",
      "a": "A logarithm answers 'what power do I raise this base to?'. Logs at arbitrary bases are computed with the change-of-base rule. The underlying maths is: log_b(x) = ln(x) ÷ ln(b)."
    },
    {
      "q": "What do I need to enter?",
      "a": "2 values: value (x), and base (b). 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 log at your base 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/exponent",
    "https://www.revenuelab.fyi/toolbox/scientific-notation"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Logarithm Calculator (https://www.revenuelab.fyi/toolbox/logarithm)"
}