{
  "id": "stone",
  "version": "26e3b9269b9b",
  "status": "published",
  "name": "Stone Calculator",
  "question": "How much stone or gravel do I need?",
  "summary": "Computes the tons and cubic yards of gravel, crushed stone or base material for an area at a chosen depth, with a waste allowance, and the cost per ton.",
  "category": "construction",
  "url": "https://www.acalculator.org/construction/stone-calculator",
  "markdown": "https://www.acalculator.org/construction/stone-calculator.md",
  "kind": "function",
  "method": "tons = area × depth × (1 + waste ÷ 100) × density ÷ 2,000 lb",
  "assumptions": [
    "Rectangle: length × width. Circle: π × diameter² ÷ 4. Triangle: base × height ÷ 2.",
    "The density is the typical loose, dry bulk density of the chosen material unless you type your own. Wet or compacted stone weighs more.",
    "Tons are US short tons of 2,000 lb; tonnes are metric tonnes of 1,000 kg.",
    "Coverage per ton is 2,000 lb ÷ (depth × density), before the waste allowance."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "shape": {
        "title": "Area shape",
        "description": "The shape of the area: a rectangle, a circle, or a triangle.",
        "type": "string",
        "enum": [
          "rectangle",
          "circle",
          "triangle"
        ]
      },
      "len": {
        "title": "Length (diameter for a circle, base for a triangle)",
        "description": "The length of a rectangle, the diameter of a circle, or the base of a triangle.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 100000
      },
      "wid": {
        "title": "Width (height for a triangle)",
        "description": "The width of a rectangle, or the height of a triangle measured square to its base.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 100000
      },
      "dep": {
        "title": "Depth",
        "description": "How thick the layer of stone is.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 10
      },
      "materialCategory": {
        "title": "Material category",
        "description": "The kind of material: decorative gravel, crushed stone, or base material.",
        "type": "string",
        "enum": [
          "decorative-gravel",
          "crushed-stone",
          "base-material"
        ]
      },
      "materialType": {
        "title": "Material",
        "description": "The decorative gravel.",
        "type": "string",
        "enum": [
          "pea-gravel",
          "river-rock-1-2",
          "decomposed-granite",
          "lava-rock-red"
        ]
      },
      "crushed": {
        "title": "Material",
        "description": "The crushed stone.",
        "type": "string",
        "enum": [
          "crushed-limestone-57",
          "crushed-sandstone"
        ]
      },
      "base": {
        "title": "Material",
        "description": "The base material.",
        "type": "string",
        "enum": [
          "road-base",
          "sand"
        ]
      },
      "density": {
        "title": "Material density",
        "description": "The weight of one cubic foot of the material. Leave empty to use the typical density of the chosen material.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "density",
        "exclusiveMinimum": 0,
        "maximum": 10000
      },
      "wasteFactor": {
        "title": "Waste allowance",
        "description": "Extra material for spills and uneven ground, as a percent of the volume.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 100
      },
      "price": {
        "title": "Price per ton",
        "description": "The price of one US ton (2,000 lb) of the material. Leave empty to skip the cost.",
        "type": "number",
        "x-unit": "USD",
        "minimum": 0,
        "maximum": 100000
      }
    }
  },
  "outputs": {
    "tons": {
      "label": "Stone to order",
      "description": "The weight to order in US short tons, waste included: volume × (1 + waste ÷ 100) × density.",
      "format": "quantity",
      "unit": "ton"
    },
    "tonnes": {
      "label": "Metric tonnes",
      "description": "The weight to order in metric tonnes (1,000 kg).",
      "format": "quantity",
      "unit": "t"
    },
    "cubicYards": {
      "label": "Volume to order",
      "description": "The volume to order, waste included, in cubic yards.",
      "format": "quantity",
      "unit": "yd3"
    },
    "area": {
      "label": "Area",
      "description": "The area of the shape.",
      "format": "quantity",
      "unit": "ft2"
    },
    "coverage": {
      "label": "Coverage per ton",
      "description": "The area one US ton covers at this depth, before the waste allowance.",
      "format": "quantity",
      "unit": "ft2"
    },
    "densityUsed": {
      "label": "Density used",
      "description": "The material density used for the weight.",
      "format": "quantity",
      "unit": "lb-ft3"
    },
    "cost": {
      "label": "Estimated cost",
      "description": "The weight to order in US tons × the price per ton.",
      "format": "money"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "shape": "rectangle",
      "len": 3.048,
      "wid": 3.048,
      "dep": 0.07619999999999999,
      "materialCategory": "decorative-gravel",
      "materialType": "pea-gravel",
      "crushed": "crushed-limestone-57",
      "base": "road-base",
      "wasteFactor": 10
    },
    "outputs": {
      "tons": 1309.747968375,
      "tonnes": 1309.747968375,
      "cubicYards": 0.7787132812800001,
      "area": 9.290304,
      "coverage": 7.0783268571428595,
      "densityUsed": 1681.9386542658144
    },
    "text": "100 ft² of stone at 3 in deep needs 1.44 tons with the waste allowance."
  },
  "examples": [
    {
      "given": {
        "shape": "rectangle",
        "len": 3.048,
        "wid": 3.048,
        "dep": 0.07619999999999999,
        "materialCategory": "decorative-gravel",
        "materialType": "pea-gravel",
        "wasteFactor": 10,
        "price": 35
      },
      "expect": {
        "tons": 1309.747968375,
        "cost": 50.53125,
        "coverage": 7.078326857142858
      },
      "source": "hand calculation in content.mdx: 100 × 0.25 × 1.1 = 27.5 ft³; × 105 lb/ft³ = 2,887.5 lb = 1.444 tons; × $35 = $50.53; 2,000 ÷ (0.25 × 105) = 76.2 ft² per ton; Engineering ToolBox, Dirt and Mud - Densities (gravel, dry 105 lb/ft³). https://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html"
    },
    {
      "given": {
        "shape": "rectangle",
        "len": 6.096,
        "wid": 3.048,
        "dep": 0.1016,
        "materialCategory": "crushed-stone",
        "crushed": "crushed-limestone-57",
        "wasteFactor": 0
      },
      "expect": {
        "tons": 2721.55422,
        "cubicYards": 1.8877897728000004
      },
      "source": "hand calculation in content.mdx: 20 × 10 × 4/12 = 66.67 ft³ = 2.47 yd³; × 90 lb/ft³ = 6,000 lb = 3 tons; Engineering ToolBox, Dirt and Mud - Densities (gravel, dry 105 lb/ft³). https://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html"
    },
    {
      "given": {
        "shape": "circle",
        "len": 3.048,
        "dep": 0.0508,
        "materialCategory": "decorative-gravel",
        "materialType": "lava-rock-red",
        "wasteFactor": 0
      },
      "expect": {
        "area": 7.296587699003969,
        "tons": 252.34418514977622
      },
      "source": "hand calculation in content.mdx: π × 10² ÷ 4 = 78.54 ft²; × 2/12 ft = 13.09 ft³; × 42.5 lb/ft³ = 556.3 lb; Engineering ToolBox, Dirt and Mud - Densities (gravel, dry 105 lb/ft³). https://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html"
    },
    {
      "given": {
        "shape": "triangle",
        "len": 4,
        "wid": 3,
        "dep": 0.1,
        "materialCategory": "base-material",
        "base": "road-base",
        "density": 1800,
        "wasteFactor": 5
      },
      "expect": {
        "area": 6,
        "tonnes": 1134.0000000000002
      },
      "source": "hand calculation in content.mdx: 4 m × 3 m ÷ 2 = 6 m²; × 0.1 m × 1.05 = 0.63 m³; × 1,800 kg/m³ = 1,134 kg; Engineering ToolBox, Dirt and Mud - Densities (gravel, dry 105 lb/ft³). https://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html"
    }
  ],
  "sources": [
    "Engineering ToolBox, Dirt and Mud - Densities (gravel, dry 105 lb/ft³). https://www.engineeringtoolbox.com/dirt-mud-densities-d_1727.html",
    "NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement: 1 cubic yard = 27 cubic feet; 1 short ton = 2,000 pounds. https://www.nist.gov/document/2026-nist-handbook-44-appendix-c"
  ],
  "related": [],
  "changelog": [
    {
      "date": "2026-09-29",
      "note": "Worked examples name a published reference for their rule."
    }
  ]
}