{
  "schemaVersion": 1,
  "slug": "horse-age-calculator",
  "category": "pets",
  "kind": "implementation",
  "independentValidation": false,
  "implementationHash": "02e605096f65f225fb1fc8f4e2f8fb8bc4ac6a10411dd3d9e78adc1bb39580f2",
  "provenance": "Generated from the calculation contract used by the published page. Publication is not external validation.",
  "sourceFiles": [
    "data/calculators/horse-age-calculator.json",
    "src/engine.js"
  ],
  "runtimeSource": "/sources/engine.txt",
  "runtimeHash": "5c888d8898afbdee36267bb9977829e1e2ac568f6677c8ee87469c139864645c",
  "scope": "The compute function records implemented equations, constants, lookup tables and custom rules. Inputs record defaults and allowed values; outputs record precision and units. Defaults are examples, not recommendations. General background references are not evidence for this specific algorithm.",
  "publishedFormula": {
    "formula": "H≈6.5×age (age≤1); otherwise H≈6.5+2.6×(age−1)",
    "vars": [
      [
        "A",
        "horse age in years"
      ],
      [
        "H",
        "equivalent human years"
      ],
      [
        "E",
        "life expectancy by use (racing 22, competition 25, general 28, retired 32)"
      ]
    ],
    "note": "Illustrative analogy H = 6.5×age for age≤1; otherwise 6.5+2.6×(age−1). Broad life-stage labels are approximate; there is no exact human-age or lifespan conversion."
  },
  "externalEvidence": {
    "reviewedAt": "2026-10-12",
    "sources": [
      {
        "name": "AAEP — Care of senior horses",
        "url": "https://aaep.org/resource/10-tips-for-caring-for-the-older-horse/"
      }
    ],
    "referenceRole": "context",
    "implementationHash": "02e605096f65f225fb1fc8f4e2f8fb8bc4ac6a10411dd3d9e78adc1bb39580f2",
    "basis": "H≈6.5×age (age≤1); otherwise H≈6.5+2.6×(age−1)",
    "limitations": "The references provide context and limitations. They do not validate this page’s illustrative multipliers, lookup values or predictions."
  },
  "contract": {
    "compute": "const humanYears=horseYears<=1?horseYears*6.5:6.5+(horseYears-1)*2.6; const stage=horseYears<1?'Foal':horseYears<2?'Yearling':horseYears<5?'Young horse, still growing':horseYears<15?'Prime adult':horseYears<20?'Mature':'Senior — watch teeth, weight and joints'; return {humanYears,lifeStage:stage};",
    "inputs": [
      {
        "name": "horseYears",
        "type": "number",
        "default": 8,
        "min": 0,
        "max": 45,
        "step": 0.5,
        "slider": true
      }
    ],
    "outputs": [
      {
        "name": "humanYears",
        "precision": 1,
        "unit": "years"
      },
      {
        "name": "lifeStage",
        "precision": 0,
        "unit": "",
        "type": "text"
      }
    ],
    "interpret": null
  }
}