{
  "id": "mortar",
  "version": "9d074f3d26be",
  "status": "published",
  "name": "Mortar Calculator",
  "question": "How many bags of mortar do I need?",
  "summary": "Estimates the bricks or blocks in a wall, the mortar volume for their joints, and the 80 lb bags of mortar mix to buy, from the wall size, unit size, joint thickness and waste.",
  "category": "construction",
  "subcategory": "materials",
  "url": "https://www.acalculator.org/construction/mortar-calculator",
  "markdown": "https://www.acalculator.org/construction/mortar-calculator.md",
  "kind": "function",
  "method": "Units = ⌈144 × wall area (ft²) ÷ ((l + j)(h + j))⌉; mortar = units × ((l + j)(h + j) − l h) × d × (1 + waste) ÷ 1,728 ft³; bags = ⌈units × (1 + waste) ÷ units per bag⌉.",
  "assumptions": [
    "A single-wythe wall, each unit with one bed joint and one head joint; cores of hollow blocks are not filled.",
    "Standard sizes: modular brick 7 5/8 × 2 1/4 × 3 5/8 in, concrete block 15 5/8 × 7 5/8 × 7 5/8 in, with 3/8 in joints.",
    "Bags use the maker’s yield (Sakrete Type S and Type N: 35 bricks or 12 blocks per 80 lb bag); yields vary with the joint and the mason.",
    "The waste allowance is yours to set; the default 10% is not from a maker."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "l": {
        "title": "Wall length (ft)",
        "description": "The length of the wall face, in feet.",
        "type": "number",
        "minimum": 0.01,
        "maximum": 100000
      },
      "h": {
        "title": "Wall height (ft)",
        "description": "The height of the wall face, in feet.",
        "type": "number",
        "minimum": 0.01,
        "maximum": 1000
      },
      "unit": {
        "title": "Laying",
        "description": "Standard modular bricks or standard 8 in concrete blocks.",
        "type": "string",
        "enum": [
          "brick",
          "block"
        ]
      },
      "ul": {
        "title": "Unit length (in, optional)",
        "description": "The actual length of one brick or block; empty uses 7 5/8 in (brick) or 15 5/8 in (block).",
        "type": "number",
        "minimum": 0.01,
        "maximum": 100
      },
      "uh": {
        "title": "Unit height (in, optional)",
        "description": "The actual height of one unit; empty uses 2 1/4 in (brick) or 7 5/8 in (block).",
        "type": "number",
        "minimum": 0.01,
        "maximum": 100
      },
      "ud": {
        "title": "Unit depth (in, optional)",
        "description": "The wall thickness, the depth of one unit; empty uses 3 5/8 in (brick) or 7 5/8 in (block).",
        "type": "number",
        "minimum": 0.01,
        "maximum": 100
      },
      "j": {
        "title": "Joint thickness (in)",
        "description": "The mortar joint; 3/8 in (0.375) is standard.",
        "type": "number",
        "minimum": 0.01,
        "maximum": 2
      },
      "pb": {
        "title": "Units per 80 lb bag (optional)",
        "description": "How many units one bag lays; empty uses the Sakrete figure: 35 bricks or 12 blocks.",
        "type": "number",
        "minimum": 0.1,
        "maximum": 10000
      },
      "w": {
        "title": "Waste allowance",
        "description": "Extra mortar for spills, droppings and mixing leftovers.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 100
      }
    }
  },
  "outputs": {
    "bags": {
      "label": "80 lb bags of mortar mix",
      "description": "⌈units × (1 + waste) ÷ units per bag⌉.",
      "format": "integer"
    },
    "units": {
      "label": "Bricks or blocks",
      "description": "⌈wall area ÷ ((unit length + joint) × (unit height + joint))⌉.",
      "format": "integer"
    },
    "volume": {
      "label": "Mortar volume (ft³)",
      "description": "The joints’ volume with the waste allowance, in cubic feet.",
      "format": "number"
    },
    "yards": {
      "label": "Mortar volume (yd³)",
      "description": "The same volume in cubic yards (27 ft³ = 1 yd³).",
      "format": "number"
    },
    "perUnit": {
      "label": "Mortar per unit (in³)",
      "description": "((length + joint)(height + joint) − length × height) × depth.",
      "format": "number"
    },
    "area": {
      "label": "Wall area (ft²)",
      "description": "Wall length × wall height.",
      "format": "number"
    },
    "name": {
      "label": "Units",
      "description": "Bricks or blocks.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "l": 20,
      "h": 4,
      "unit": "brick",
      "j": 0.375,
      "w": 10
    },
    "outputs": {
      "bags": 18,
      "units": 549,
      "volume": 4.869500732421875,
      "yards": 0.18035187897858795,
      "perUnit": 13.93359375,
      "area": 80,
      "name": "bricks"
    },
    "text": "For 549 bricks, buy about 18 80 lb bags of mortar mix."
  },
  "examples": [
    {
      "given": {
        "l": 20,
        "h": 4,
        "unit": "brick",
        "j": 0.375,
        "w": 10
      },
      "expect": {
        "units": 549,
        "bags": 18,
        "perUnit": 13.93359375,
        "volume": 4.869500732421875,
        "area": 80
      },
      "source": "hand calculation in content.mdx: 11,520 in² ÷ 21 in² = 548.6, so 549 bricks; 549 × 1.1 ÷ 35 = 17.25, so 18 bags; Sakrete, Mortar Mix Type S (an 80 lb bag lays 12 standard 8 in blocks or 35 standard bricks), https://www.sakrete.com/product/mortar-mix-type-s/ (retrieved 2026-10-02)"
    },
    {
      "given": {
        "l": 32,
        "h": 6,
        "unit": "block",
        "j": 0.375,
        "w": 0
      },
      "expect": {
        "units": 216,
        "bags": 18,
        "perUnit": 67.552734375,
        "volume": 8.444091796875,
        "yards": 0.312744140625
      },
      "source": "hand calculation in content.mdx: 27,648 in² ÷ 128 in² = 216 blocks; 216 ÷ 12 = 18 bags; Sakrete, Mortar Mix Type N (an 80 lb bag lays 12 standard 8 in blocks or 35 standard bricks), https://www.sakrete.com/product/mortar-mix-type-n/ (retrieved 2026-10-02)"
    },
    {
      "given": {
        "l": 10,
        "h": 3,
        "unit": "brick",
        "j": 0.5,
        "pb": 37,
        "w": 5
      },
      "expect": {
        "units": 194,
        "bags": 6,
        "perUnit": 18.8046875
      },
      "source": "hand calculation in content.mdx: 4,320 in² ÷ (8.125 × 2.75) = 193.3, so 194 bricks; 194 × 1.05 ÷ 37 = 5.51, so 6 bags; Sakrete, Mortar Mix Type S (an 80 lb bag lays 12 standard 8 in blocks or 35 standard bricks), https://www.sakrete.com/product/mortar-mix-type-s/ (retrieved 2026-10-02)"
    }
  ],
  "sources": [
    "Sakrete, Mortar Mix Type S (product page: an 80 lb bag lays 12 standard 8 in blocks or 35 standard bricks, or sets 10 ft² of cultured stone). https://www.sakrete.com/product/mortar-mix-type-s/ (retrieved 2026-10-02)",
    "Sakrete, Mortar Mix Type N (product page: an 80 lb bag lays 12 standard 8 in blocks or 35 standard bricks). https://www.sakrete.com/product/mortar-mix-type-n/ (retrieved 2026-10-02)"
  ],
  "related": [
    "concrete-block",
    "concrete",
    "paver"
  ],
  "changelog": []
}