{
  "schemaVersion": 1,
  "slug": "lawn-mowing-time-calculator",
  "category": "gardening",
  "kind": "implementation",
  "independentValidation": false,
  "implementationHash": "617eb998612a0f5dd2771b7a42d708508b7aa45edec568341a26cd3c35a5f007",
  "provenance": "Generated from the calculation contract used by the published page. Publication is not external validation.",
  "sourceFiles": [
    "data/calculators/lawn-mowing-time-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": "t = A ÷ (R_m ÷ O ÷ b)",
    "vars": [],
    "note": "R_m: mower rate (sq ft/min); O: obstacle factor; b: bagging factor (1.15 when bagging). Annual hours = session time × user-entered sessions per year ÷ 60. These fixed rates are rough assumptions; energy cost is not calculated."
  },
  "externalEvidence": {
    "reviewedAt": "2026-10-12",
    "sources": [
      {
        "name": "University of Minnesota Extension — Mowing practices",
        "url": "https://extension.umn.edu/lawn-care/mowing-practices-healthy-lawns"
      }
    ],
    "referenceRole": "input",
    "implementationHash": "617eb998612a0f5dd2771b7a42d708508b7aa45edec568341a26cd3c35a5f007",
    "basis": "t = A ÷ (R_m ÷ O ÷ b)",
    "limitations": "Use the cited guidance and your own measurements, bills or product specifications to choose inputs. Sample defaults are not current local data."
  },
  "contract": {
    "compute": "const R={push:400,selfPropelled:700,riding:2500,robot:180,battery:450}; const O={none:1,some:1.25,many:1.6}; const bagFactor=bagging==='yes'?1.15:1; const rate=(R[mowerType]||400)/(O[obstacles]||1)/bagFactor; const minutes=area/rate; return {minutes,sessionsPerYear,yearlyHours:minutes*sessionsPerYear/60};",
    "inputs": [
      {
        "name": "area",
        "type": "number",
        "default": 5000,
        "min": 10,
        "max": 500000,
        "step": 10
      },
      {
        "name": "mowerType",
        "type": "select",
        "default": "push",
        "options": [
          {
            "value": "push"
          },
          {
            "value": "selfPropelled"
          },
          {
            "value": "riding"
          },
          {
            "value": "robot"
          },
          {
            "value": "battery"
          }
        ]
      },
      {
        "name": "obstacles",
        "type": "select",
        "default": "some",
        "options": [
          {
            "value": "none"
          },
          {
            "value": "some"
          },
          {
            "value": "many"
          }
        ]
      },
      {
        "name": "bagging",
        "type": "select",
        "default": "no",
        "options": [
          {
            "value": "no"
          },
          {
            "value": "yes"
          }
        ]
      },
      {
        "name": "sessionsPerYear",
        "type": "number",
        "default": 28,
        "min": 1,
        "max": 365,
        "step": 1
      }
    ],
    "outputs": [
      {
        "name": "minutes",
        "precision": 0,
        "unit": "min"
      },
      {
        "name": "sessionsPerYear",
        "precision": 0,
        "unit": "sessions"
      },
      {
        "name": "yearlyHours",
        "precision": 1,
        "unit": "h"
      }
    ],
    "interpret": null
  }
}