{
  "schemaVersion": 1,
  "slug": "pressure-washer-calculator",
  "category": "cleaning",
  "kind": "implementation",
  "independentValidation": false,
  "implementationHash": "474f90a07e82901615d0bb9cfa0423b6f5bf9e2ca444fb911b0b5b3604018875",
  "provenance": "Generated from the calculation contract used by the published page. Publication is not external validation.",
  "sourceFiles": [
    "data/calculators/pressure-washer-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": "C = (p ÷ 12)(1 − o ÷ 100) × v; T = A ÷ C × n + s; Q = T × f",
    "vars": [
      [
        "C",
        "Coverage rate (ft²/min)"
      ],
      [
        "p",
        "Pass width (in)"
      ],
      [
        "o",
        "Overlap (%)"
      ],
      [
        "v",
        "Walk speed (ft/min)"
      ],
      [
        "A",
        "Area (ft²)"
      ],
      [
        "Q",
        "Water used (gal)"
      ],
      [
        "T",
        "Total time (min)"
      ],
      [
        "n",
        "Number of passes"
      ],
      [
        "s",
        "Setup time (min)"
      ],
      [
        "f",
        "Flow rate (gal/min)"
      ]
    ],
    "note": "Effective pass width = pass width × (1 − overlap fraction); coverage = effective width × walking speed; cleaning time = area / coverage × passes. Water = cleaning time × flow rate, excluding setup time. This assumes uninterrupted spraying and steady pace."
  },
  "externalEvidence": {
    "reviewedAt": "2026-10-12",
    "sources": [
      {
        "name": "CDC — Pressure washer safety",
        "url": "https://www.cdc.gov/natural-disasters/safety/pressure-washer-safety.html"
      }
    ],
    "referenceRole": "context",
    "implementationHash": "474f90a07e82901615d0bb9cfa0423b6f5bf9e2ca444fb911b0b5b3604018875",
    "basis": "C = (p ÷ 12)(1 − o ÷ 100) × v; T = A ÷ C × n + s; Q = T × f",
    "limitations": "The references provide context and limitations. They do not validate this page’s illustrative multipliers, lookup values or predictions."
  },
  "contract": {
    "compute": "const effWidth = passWidth/12*(1 - overlapPct/100); const coverage = effWidth*walkSpeed; const cleaning = coverage > 0 ? area/coverage*passes : 0; const total = cleaning + setupMinutes; const gallons = cleaning*flowRate; return { coveragePerMinute: coverage, cleaningMinutes: cleaning, totalMinutes: total, gallonsUsed: gallons, waterCostTotal: gallons/1000*waterCost, advice: passWidth < 10 ? 'Narrow pass — expect a slow job' : passWidth > 30 ? 'Wide pass covers fast but may need a second pass on tough dirt' : 'Reasonable pass width for a home job' };",
    "inputs": [
      {
        "name": "area",
        "type": "number",
        "default": 1000,
        "min": 10,
        "max": 1000000,
        "step": 10
      },
      {
        "name": "passWidth",
        "type": "number",
        "default": 12,
        "min": 1,
        "max": 60,
        "step": 1,
        "slider": true
      },
      {
        "name": "walkSpeed",
        "type": "number",
        "default": 20,
        "min": 1,
        "max": 300,
        "step": 1,
        "slider": true
      },
      {
        "name": "flowRate",
        "type": "number",
        "default": 1.4,
        "min": 0.1,
        "max": 10,
        "step": 0.1,
        "slider": true
      },
      {
        "name": "overlapPct",
        "type": "number",
        "default": 20,
        "min": 0,
        "max": 80,
        "step": 5,
        "slider": true
      },
      {
        "name": "passes",
        "type": "number",
        "default": 1,
        "min": 1,
        "max": 5,
        "step": 1
      },
      {
        "name": "setupMinutes",
        "type": "number",
        "default": 15,
        "min": 0,
        "max": 180,
        "step": 5,
        "slider": true
      },
      {
        "name": "waterCost",
        "type": "number",
        "default": 6,
        "min": 0,
        "max": 200,
        "step": 0.1,
        "slider": true
      }
    ],
    "outputs": [
      {
        "name": "coveragePerMinute",
        "precision": 1,
        "unit": "sq ft/min"
      },
      {
        "name": "cleaningMinutes",
        "precision": 1,
        "unit": "minutes"
      },
      {
        "name": "totalMinutes",
        "precision": 1,
        "unit": "minutes"
      },
      {
        "name": "gallonsUsed",
        "precision": 1,
        "unit": "gallons"
      },
      {
        "name": "waterCostTotal",
        "precision": 2,
        "unit": "$"
      },
      {
        "name": "advice",
        "precision": 0,
        "unit": "",
        "type": "text"
      }
    ],
    "interpret": null
  }
}