{
  "schemaVersion": 1,
  "slug": "acres-hectares-calculator",
  "category": "conversion",
  "kind": "implementation",
  "independentValidation": false,
  "implementationHash": "608a4f42ac7c8d99ac63f5fc9de53f21a60ab8320c8ab6ce82a52d44474da7ea",
  "provenance": "Generated from the calculation contract used by the published page. Publication is not external validation.",
  "sourceFiles": [
    "data/calculators/acres-hectares-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": "ha = ac ÷ 2.471053814671653",
    "vars": [
      [
        "ha",
        "area in hectares"
      ],
      [
        "ac",
        "area in acres"
      ]
    ],
    "note": "1 hectare = 10,000 m² ≈ 107,639.10 ft²; 1 acre ≈ 0.404686 ha. Displayed values are rounded."
  },
  "externalEvidence": {
    "reviewedAt": "2026-10-04",
    "sources": [
      {
        "name": "NIST SP 811 — Conversion factors by quantity",
        "url": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9"
      }
    ],
    "basis": "1 hectare = 10000 square metres; 1 international acre = 4046.8564224 square metres.",
    "limitations": "Only the displayed unit definitions are converted; rounding and measurement uncertainty are separate.",
    "implementationHash": "608a4f42ac7c8d99ac63f5fc9de53f21a60ab8320c8ab6ce82a52d44474da7ea",
    "domain": "conversion"
  },
  "contract": {
    "compute": "const F={\"ac\":4046.8564224,\"ha\":10000}, U={\"ac\":\"ac\",\"ha\":\"ha\"}, L={\"ac2ha\":[\"ac\",\"ha\"],\"ha2ac\":[\"ha\",\"ac\"]}; const pair=Object.prototype.hasOwnProperty.call(L,direction)?L[direction]:[from,to], source=pair[0], target=pair[1]; if(!Number.isFinite(value)||value<-1000000000000||value>1000000000000||!Object.prototype.hasOwnProperty.call(F,source)||!Object.prototype.hasOwnProperty.call(F,target))return {\"result\":null,\"acres\":null,\"hectares\":null,\"squareMetres\":null,\"squareFeet\":null,\"__error\":\"inputError\"}; const base=value*F[source], out=(function(value,direction){const acres = direction === 'ac2ha' ? value : value*2.471053814671653; const hectares = acres/2.471053814671653; return { result: direction === 'ac2ha' ? hectares : acres, acres, hectares, squareMetres: hectares*10000, squareFeet: hectares*107639.104167 };})(base/F[\"ac\"],\"ac2ha\"); if(out.__error)return {...{\"result\":null,\"acres\":null,\"hectares\":null,\"squareMetres\":null,\"squareFeet\":null},...out}; out.result=value*(F[source]/F[target]);out.__resultUnit=U[target];out.__unitRatio=F[target]/F[source];return out;",
    "inputs": [
      {
        "name": "value",
        "type": "number",
        "default": 10,
        "min": -1000000000000,
        "max": 1000000000000,
        "step": 0.01,
        "requiredValue": true,
        "strictRange": true
      },
      {
        "name": "direction",
        "type": "select",
        "default": "auto",
        "options": [
          {
            "value": "auto"
          },
          {
            "value": "ac2ha"
          },
          {
            "value": "ha2ac"
          }
        ],
        "showWhen": {
          "from": []
        }
      },
      {
        "name": "precision",
        "type": "select",
        "default": 4,
        "options": [
          {
            "value": 0
          },
          {
            "value": 2
          },
          {
            "value": 4
          },
          {
            "value": 6
          }
        ]
      },
      {
        "name": "from",
        "type": "select",
        "default": "ac",
        "options": [
          {
            "value": "ac"
          },
          {
            "value": "ha"
          }
        ]
      },
      {
        "name": "to",
        "type": "select",
        "default": "ha",
        "options": [
          {
            "value": "ha"
          },
          {
            "value": "ac"
          }
        ]
      }
    ],
    "outputs": [
      {
        "name": "result",
        "precision": 4,
        "unit": "",
        "precisionField": "precision",
        "unitField": "__resultUnit",
        "trimTrailingZeros": true,
        "notation": "auto"
      },
      {
        "name": "acres",
        "precision": 4,
        "unit": "ac",
        "showWhen": {
          "to": [
            "ha"
          ]
        },
        "notation": "auto"
      },
      {
        "name": "hectares",
        "precision": 4,
        "unit": "ha",
        "showWhen": {
          "to": [
            "ac"
          ]
        },
        "notation": "auto"
      },
      {
        "name": "squareMetres",
        "precision": 2,
        "unit": "m²",
        "notation": "auto"
      },
      {
        "name": "squareFeet",
        "precision": 2,
        "unit": "ft²",
        "notation": "auto"
      }
    ],
    "interpret": null
  }
}