{
  "slug": "12x20-concrete-slab-calculator",
  "title": "12x20 Concrete Slab Calculator",
  "heading": "12x20 Concrete Slab Calculator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/12x20-concrete-slab-calculator",
  "summary": "Yardage, bags, and cost for a 12x20 single-car parking pad or workshop slab.",
  "description": "12 by 20 feet is the standard single-car parking pad and a common workshop or carport slab. At 240 square feet it sits right at the point where hand-mixing bags stops making sense and a ready-mix truck becomes the obvious call. This calculator defaults to 12x20 at 4 inches thick, but bump the thickness to 5 or 6 inches if a vehicle heavier than a passenger car will park on it, since load capacity scales with thickness and with the compacted base underneath. It returns cubic yards to order, the equivalent 80-lb bag count, total cubic footage, and the estimated ready-mix cost at your local price.",
  "formula": "Cubic Yards = (Length × Width × Thickness ÷ 12) ÷ 27 × (1 + Waste%). Bags (80lb) ≈ Cubic Yards × 45. Cost = Cubic Yards × Price per Yard.",
  "dateModified": "2026-09-06",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=12x20-concrete-slab-calculator",
  "inputs": [
    {
      "id": "length",
      "label": "Slab length",
      "kind": "number",
      "hint": null,
      "default": 20,
      "unit": "ft",
      "min": 1,
      "max": null
    },
    {
      "id": "width",
      "label": "Slab width",
      "kind": "number",
      "hint": null,
      "default": 12,
      "unit": "ft",
      "min": 1,
      "max": null
    },
    {
      "id": "thickness",
      "label": "Thickness",
      "kind": "number",
      "hint": null,
      "default": 4,
      "unit": "in",
      "min": 2,
      "max": 12
    },
    {
      "id": "waste",
      "label": "Waste factor",
      "kind": "number",
      "hint": null,
      "default": 10,
      "unit": "%",
      "min": 0,
      "max": 30
    },
    {
      "id": "pricePerYard",
      "label": "Ready-mix price per cubic yard",
      "kind": "number",
      "hint": null,
      "default": 165,
      "unit": "$",
      "min": 0,
      "max": null
    }
  ],
  "outputs": [
    {
      "id": "cubicYards",
      "label": "Ready-mix needed",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "bags",
      "label": "80-lb bags (DIY mix)",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "cost",
      "label": "Estimated concrete cost",
      "format": "currency",
      "hint": null,
      "primary": false
    },
    {
      "id": "cubicFeet",
      "label": "Total cubic feet",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Slab length: 20 ft",
      "Slab width: 12 ft",
      "Thickness: 4 in",
      "Waste factor: 10 %",
      "Ready-mix price per cubic yard: 165 $"
    ],
    "outputs": [
      "Ready-mix needed: 3.26",
      "80-lb bags (DIY mix): 147",
      "Estimated concrete cost: $538",
      "Total cubic feet: 80"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter slab length (ft).",
      "Enter slab width (ft).",
      "Enter thickness (in).",
      "Enter waste factor (%).",
      "Enter ready-mix price per cubic yard ($).",
      "Read your ready-mix needed on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "length": 12,
        "width": 7,
        "thickness": 2.4,
        "waste": 6,
        "pricePerYard": 100
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "length": 20,
        "width": 12,
        "thickness": 4,
        "waste": 10,
        "pricePerYard": 165
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "length": 32,
        "width": 19,
        "thickness": 6.4,
        "waste": 16,
        "pricePerYard": 265
      }
    }
  ],
  "limitations": [
    "Estimates assume standard, average conditions — local rules, pricing, and materials vary.",
    "Results are rounded for readability; add a buffer before ordering, booking, or committing.",
    "Double-check anything with a real cost attached against a local quote."
  ],
  "faq": [
    {
      "q": "How thick should a 12x20 parking pad be?",
      "a": "Four inches works for passenger cars over a compacted base. Go to five or six inches with rebar if a truck, RV, or trailer will sit on it."
    },
    {
      "q": "How many yards is a 12x20 slab?",
      "a": "At 4 inches thick it is about 3 cubic yards before waste, roughly 3.3 with a 10% factor — well within a single ready-mix delivery."
    },
    {
      "q": "Do I need rebar?",
      "a": "Wire mesh or a grid of #3-#4 rebar is cheap insurance on a pad this size, especially in freeze-thaw climates or anywhere vehicles park."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/20x20-concrete-slab-calculator",
    "https://www.revenuelab.fyi/toolbox/10x20-driveway-apron-calculator"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — 12x20 Concrete Slab Calculator (https://www.revenuelab.fyi/toolbox/12x20-concrete-slab-calculator)"
}