{
  "slug": "concrete-sonotube-piers-calculator",
  "title": "Sonotube Concrete Piers Calculator",
  "heading": "Sonotube Concrete Piers Calculator",
  "category": "other",
  "url": "https://www.revenuelab.fyi/toolbox/concrete-sonotube-piers-calculator",
  "summary": "Cubic yards and bags for round cardboard-form footings under a deck or porch.",
  "description": "Sonotube (cardboard cylinder) forms are the standard way to pour round concrete footings under deck posts, porches, and pergolas, and because the form is a perfect cylinder the math is straightforward once you know tube diameter and pour depth. This calculator takes tube diameter and depth, computes cylindrical volume in cubic feet using π×r²×depth, multiplies by your pier count, then converts to both cubic yards for ready-mix ordering and 80lb bags for hand-mixing, since most sonotube jobs (6-12 piers) sit right at the boundary between the two approaches. Common deck footing tubes run 8, 10, or 12 inches in diameter depending on local frost depth code and the load path from beams above, and depth is usually set to your area's frost line, often 36-48 inches in cold climates. A waste factor is included since tubes are rarely trimmed to an exact depth and a little overpour above grade is normal for crowning the top of the footing.",
  "formula": "Volume per Pier = π × (Diameter/2)² × Depth. Total Volume = Volume per Pier × Pier Count. Bags = ceil((Total ÷ 0.6) × (1 + Waste%)).",
  "dateModified": "2026-09-06",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=concrete-sonotube-piers-calculator",
  "inputs": [
    {
      "id": "diameter",
      "label": "Tube diameter",
      "kind": "number",
      "hint": null,
      "default": 10,
      "unit": "in",
      "min": 6,
      "max": 24
    },
    {
      "id": "depth",
      "label": "Pour depth",
      "kind": "number",
      "hint": null,
      "default": 42,
      "unit": "in",
      "min": 6,
      "max": 72
    },
    {
      "id": "pierCount",
      "label": "Number of piers",
      "kind": "number",
      "hint": null,
      "default": 6,
      "unit": null,
      "min": 1,
      "max": 60
    },
    {
      "id": "wastePct",
      "label": "Waste factor",
      "kind": "number",
      "hint": null,
      "default": 8,
      "unit": "%",
      "min": 0,
      "max": 25
    }
  ],
  "outputs": [
    {
      "id": "cubicYards",
      "label": "Ready-mix needed",
      "format": "decimal",
      "hint": "cu yd",
      "primary": true
    },
    {
      "id": "bags80",
      "label": "Equivalent 80lb bags",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "volPerPier",
      "label": "Volume per pier",
      "format": "decimal",
      "hint": "cu ft",
      "primary": false
    },
    {
      "id": "totalCubicFeet",
      "label": "Total cubic feet",
      "format": "decimal",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Tube diameter: 10 in",
      "Pour depth: 42 in",
      "Number of piers: 6",
      "Waste factor: 8 %"
    ],
    "outputs": [
      "Ready-mix needed: 0.46",
      "Equivalent 80lb bags: 21",
      "Volume per pier: 1.91",
      "Total cubic feet: 12.4"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter tube diameter (in).",
      "Enter pour depth (in).",
      "Enter number of piers.",
      "Enter waste factor (%).",
      "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": {
        "diameter": 6,
        "depth": 25,
        "pierCount": 4,
        "wastePct": 5
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "diameter": 10,
        "depth": 42,
        "pierCount": 6,
        "wastePct": 8
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "diameter": 16,
        "depth": 67,
        "pierCount": 10,
        "wastePct": 13
      }
    }
  ],
  "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 deep should sonotube footings be poured?",
      "a": "Deep enough to sit below your local frost line — often 36-48 inches in northern climates and as little as 12 inches in frost-free southern regions — always check local building code since frost heave can crack footings poured too shallow."
    },
    {
      "q": "What diameter tube do I need for a deck post?",
      "a": "8-10 inches is common for typical residential deck posts; larger structures or beam spans requiring higher point loads may call for 12+ inch tubes per an engineer's or code table's load requirements."
    },
    {
      "q": "Is it cheaper to hand-mix bags or order ready-mix for sonotube piers?",
      "a": "Under about 8-10 piers, bagged mix is usually more practical since a ready-mix truck minimum often exceeds what a handful of tube footings need; beyond that, a small ready-mix order or short-load delivery starts to pay off."
    },
    {
      "q": "Do I need rebar in sonotube piers?",
      "a": "Most codes require a vertical rebar cage or post anchor embedded in the footing for structural connections; check local code, but adding rebar is cheap insurance regardless of the minimum requirement."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/concrete-fence-post-calculator",
    "https://www.revenuelab.fyi/toolbox/concrete-bags-80lb-calculator",
    "https://www.revenuelab.fyi/toolbox/rebar-length-calculator"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Sonotube Concrete Piers Calculator (https://www.revenuelab.fyi/toolbox/concrete-sonotube-piers-calculator)"
}