{
  "dataset": "tools",
  "title": "Free caffeine calculators",
  "description": "Four calculators that run entirely in the reader's browser, on the same model this site publishes at /api/v1/model.json. No account, no upload, nothing sent anywhere.",
  "generated": "2026-09-30",
  "count": 4,
  "self": "https://trackcaffeine.com/api/v1/tools.json",
  "documentation": "https://trackcaffeine.com/api/",
  "licence": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "TrackCaffeine (https://trackcaffeine.com)",
    "terms": "Free to reuse, redistribute and build on, including commercially, with attribution to TrackCaffeine and a link to https://trackcaffeine.com."
  },
  "provenance": {
    "compiled_by": "Vast Flow, LLP",
    "method": "Caffeine figures are compiled by hand from manufacturer labelling and nutrition panels, USDA FoodData Central and published measurement tables, for the serving size named in the row. Everything derived — decay, cutoff times, cup equivalents — is computed from the published model, not taken from a source.",
    "licensed_in_data": false,
    "licensed_in_note": "No column here is redistributed from a third-party API or a licensed corpus, which is why the whole set can carry CC BY 4.0. Brand names identify the product a row describes.",
    "primary_sources": [
      {
        "name": "FDA — Spilling the Beans: How Much Caffeine is Too Much?",
        "url": "https://www.fda.gov/consumers/consumer-updates/spilling-beans-how-much-caffeine-too-much"
      },
      {
        "name": "EFSA — Scientific Opinion on the Safety of Caffeine (2015)",
        "url": "https://www.efsa.europa.eu/en/efsajournal/pub/4102"
      },
      {
        "name": "USDA FoodData Central",
        "url": "https://fdc.nal.usda.gov/"
      },
      {
        "name": "Drake et al., Journal of Clinical Sleep Medicine (2013)",
        "url": "https://jcsm.aasm.org/doi/10.5664/jcsm.3170"
      }
    ],
    "contact": "support@trackcaffeine.com"
  },
  "model": "https://trackcaffeine.com/api/v1/model.json",
  "mcp": "https://trackcaffeine.com/mcp",
  "note": "Every `mcp_tool` named here exists on the MCP server and computes with the same engine module as the page. Sending a person to the page and calling the tool give the same figure; the page is better when they want to try several inputs.",
  "data": [
    {
      "slug": "caffeine-calculator",
      "name": "Caffeine half-life calculator",
      "title": "Caffeine calculator: how much is in your system right now",
      "description": "Add the drinks you had and see how much caffeine is in your system now, at bedtime, and the latest cup you can still have before it touches your sleep.",
      "cluster": "Metabolism & sleep",
      "url": "https://trackcaffeine.com/tools/caffeine-calculator/",
      "markdown": "https://trackcaffeine.com/tools/caffeine-calculator/index.md",
      "localized_urls": {
        "en": "https://trackcaffeine.com/tools/caffeine-calculator/",
        "es": "https://trackcaffeine.com/es/tools/caffeine-calculator/",
        "pt": "https://trackcaffeine.com/pt/tools/caffeine-calculator/",
        "fr": "https://trackcaffeine.com/fr/tools/caffeine-calculator/",
        "de": "https://trackcaffeine.com/de/tools/caffeine-calculator/",
        "it": "https://trackcaffeine.com/it/tools/caffeine-calculator/",
        "nl": "https://trackcaffeine.com/nl/tools/caffeine-calculator/",
        "pl": "https://trackcaffeine.com/pl/tools/caffeine-calculator/",
        "tr": "https://trackcaffeine.com/tr/tools/caffeine-calculator/",
        "id": "https://trackcaffeine.com/id/tools/caffeine-calculator/",
        "ja": "https://trackcaffeine.com/ja/tools/caffeine-calculator/",
        "ko": "https://trackcaffeine.com/ko/tools/caffeine-calculator/"
      },
      "runs_in_browser": true,
      "requires_account": false,
      "sends_anything_to_a_server": false,
      "inputs": [
        "one or more drinks with the time each was drunk",
        "half-life in hours (1–12)",
        "bedtime"
      ],
      "outputs": [
        "mg in system now",
        "mg at bedtime",
        "latest cup that stays under the threshold",
        "decay at +1/+3/+6/+12 h"
      ],
      "engine": [
        "caffeineAt",
        "nextBedtime",
        "latestCutoff",
        "decayTable"
      ],
      "mcp_tool": "caffeine_now",
      "faq": [
        {
          "question": "How is caffeine in the body calculated?",
          "answer": "Each dose follows first-order decay: mg remaining = dose × 0.5^(minutes ÷ half-life). The calculator adds up every dose at the time you ask, the same way the CoffeeLog app does."
        },
        {
          "question": "What is the half-life of caffeine?",
          "answer": "On average about 5.7 hours in healthy adults, meaning half the caffeine is gone after ~5.7 hours. It varies widely — smoking, some medications and genetics can move it from roughly 1.5 to 10+ hours."
        },
        {
          "question": "How much caffeine is too much before bed?",
          "answer": "Many people sleep poorly with more than about 100 mg still in their system at bedtime. The calculator marks the latest time you can have a standard cup and still stay under that line."
        },
        {
          "question": "Is this medical advice?",
          "answer": "No. It is an estimate for general information using population-average pharmacokinetics. Individual metabolism varies; talk to a professional for medical concerns."
        }
      ]
    },
    {
      "slug": "last-cup-before-bed",
      "name": "Last cup before bed",
      "title": "Last cup before bed: when to stop drinking caffeine",
      "description": "Find the latest time you can have a coffee and still fall below the caffeine level that disturbs sleep by your bedtime.",
      "cluster": "Metabolism & sleep",
      "url": "https://trackcaffeine.com/tools/last-cup-before-bed/",
      "markdown": "https://trackcaffeine.com/tools/last-cup-before-bed/index.md",
      "localized_urls": {
        "en": "https://trackcaffeine.com/tools/last-cup-before-bed/",
        "es": "https://trackcaffeine.com/es/tools/last-cup-before-bed/",
        "pt": "https://trackcaffeine.com/pt/tools/last-cup-before-bed/",
        "fr": "https://trackcaffeine.com/fr/tools/last-cup-before-bed/",
        "de": "https://trackcaffeine.com/de/tools/last-cup-before-bed/",
        "it": "https://trackcaffeine.com/it/tools/last-cup-before-bed/",
        "nl": "https://trackcaffeine.com/nl/tools/last-cup-before-bed/",
        "pl": "https://trackcaffeine.com/pl/tools/last-cup-before-bed/",
        "tr": "https://trackcaffeine.com/tr/tools/last-cup-before-bed/",
        "id": "https://trackcaffeine.com/id/tools/last-cup-before-bed/",
        "ja": "https://trackcaffeine.com/ja/tools/last-cup-before-bed/",
        "ko": "https://trackcaffeine.com/ko/tools/last-cup-before-bed/"
      },
      "runs_in_browser": true,
      "requires_account": false,
      "sends_anything_to_a_server": false,
      "inputs": [
        "bedtime",
        "caffeine already drunk today, with times",
        "half-life in hours"
      ],
      "outputs": [
        "the latest clock time a standard cup still leaves you under 100 mg at bedtime"
      ],
      "engine": [
        "latestCutoff"
      ],
      "mcp_tool": "last_cup_before_bed",
      "faq": [
        {
          "question": "How many hours before bed should I stop caffeine?",
          "answer": "A common guideline is 8–10 hours, but it depends on the dose and your metabolism. From a 95 mg cup it takes under an hour to clear the 100 mg sleep line if you have had nothing else; from a large energy drink it can be many hours."
        },
        {
          "question": "Why does afternoon coffee affect sleep?",
          "answer": "With a 5.7-hour half-life, about a quarter of a 2 pm coffee is still circulating near midnight. Even when you do not feel wired, that residual caffeine can reduce deep sleep."
        },
        {
          "question": "Does caffeine before bed really reduce sleep quality?",
          "answer": "Yes. Studies show caffeine taken even 6 hours before bed can cut total sleep time and reduce deep sleep, often without the person noticing. The effect is on sleep architecture, not just falling asleep."
        }
      ]
    },
    {
      "slug": "safe-daily-limit",
      "name": "Safe daily caffeine limit",
      "title": "Safe daily caffeine limit by body weight",
      "description": "See a personalized safe caffeine ceiling based on body weight, alongside the general FDA 400 mg/day guideline.",
      "cluster": "Dose & safety",
      "url": "https://trackcaffeine.com/tools/safe-daily-limit/",
      "markdown": "https://trackcaffeine.com/tools/safe-daily-limit/index.md",
      "localized_urls": {
        "en": "https://trackcaffeine.com/tools/safe-daily-limit/",
        "es": "https://trackcaffeine.com/es/tools/safe-daily-limit/",
        "pt": "https://trackcaffeine.com/pt/tools/safe-daily-limit/",
        "fr": "https://trackcaffeine.com/fr/tools/safe-daily-limit/",
        "de": "https://trackcaffeine.com/de/tools/safe-daily-limit/",
        "it": "https://trackcaffeine.com/it/tools/safe-daily-limit/",
        "nl": "https://trackcaffeine.com/nl/tools/safe-daily-limit/",
        "pl": "https://trackcaffeine.com/pl/tools/safe-daily-limit/",
        "tr": "https://trackcaffeine.com/tr/tools/safe-daily-limit/",
        "id": "https://trackcaffeine.com/id/tools/safe-daily-limit/",
        "ja": "https://trackcaffeine.com/ja/tools/safe-daily-limit/",
        "ko": "https://trackcaffeine.com/ko/tools/safe-daily-limit/"
      },
      "runs_in_browser": true,
      "requires_account": false,
      "sends_anything_to_a_server": false,
      "inputs": [
        "body weight in kg or lb"
      ],
      "outputs": [
        "moderate daily band (≈3 mg/kg)",
        "upper band (≈6 mg/kg)",
        "the flat 400 mg guidance in cups"
      ],
      "engine": [
        "weightLimits"
      ],
      "mcp_tool": "daily_limit",
      "faq": [
        {
          "question": "What is the safe daily caffeine limit?",
          "answer": "The FDA cites up to 400 mg per day for most healthy adults — about four cups of brewed coffee. Pregnant people are usually advised to stay under about 200 mg per day."
        },
        {
          "question": "Does body weight change my caffeine limit?",
          "answer": "It can. Tolerability is often described as roughly 3–6 mg per kg, so a heavier person may tolerate more in a single dose. Sensitivity, sleep and medication still matter more than weight alone."
        }
      ]
    },
    {
      "slug": "caffeine-comparison",
      "name": "Compare two drinks",
      "title": "Caffeine comparison: put two drinks side by side",
      "description": "Compare the caffeine content of any two drinks and see the difference in mg and cups of coffee.",
      "cluster": "Comparison & converters",
      "url": "https://trackcaffeine.com/tools/caffeine-comparison/",
      "markdown": "https://trackcaffeine.com/tools/caffeine-comparison/index.md",
      "localized_urls": {
        "en": "https://trackcaffeine.com/tools/caffeine-comparison/",
        "es": "https://trackcaffeine.com/es/tools/caffeine-comparison/",
        "pt": "https://trackcaffeine.com/pt/tools/caffeine-comparison/",
        "fr": "https://trackcaffeine.com/fr/tools/caffeine-comparison/",
        "de": "https://trackcaffeine.com/de/tools/caffeine-comparison/",
        "it": "https://trackcaffeine.com/it/tools/caffeine-comparison/",
        "nl": "https://trackcaffeine.com/nl/tools/caffeine-comparison/",
        "pl": "https://trackcaffeine.com/pl/tools/caffeine-comparison/",
        "tr": "https://trackcaffeine.com/tr/tools/caffeine-comparison/",
        "id": "https://trackcaffeine.com/id/tools/caffeine-comparison/",
        "ja": "https://trackcaffeine.com/ja/tools/caffeine-comparison/",
        "ko": "https://trackcaffeine.com/ko/tools/caffeine-comparison/"
      },
      "runs_in_browser": true,
      "requires_account": false,
      "sends_anything_to_a_server": false,
      "inputs": [
        "two drinks from the dataset"
      ],
      "outputs": [
        "mg each",
        "mg per 100 ml",
        "cups of drip coffee",
        "what is left after 6 and 12 hours",
        "the ratio between them"
      ],
      "engine": [
        "remainingAfter",
        "cupEquivalent"
      ],
      "mcp_tool": "compare_drinks",
      "faq": [
        {
          "question": "Does Red Bull have more caffeine than coffee?",
          "answer": "Per serving, usually not. A 250 ml Red Bull has 80 mg, while an 8 oz cup of brewed coffee has about 96 mg. Energy drinks feel stronger mainly because of sugar and carbonation."
        }
      ]
    }
  ]
}