{
  "id": "grout",
  "version": "86803e6d427d",
  "status": "published",
  "name": "Grout Calculator",
  "question": "How much grout do I need?",
  "summary": "Computes how much tile grout to buy, in pounds, kilograms and bags, from the tiled area, tile size, joint width and depth, the grout’s density and a waste allowance.",
  "category": "construction",
  "subcategory": "flooring",
  "url": "https://www.acalculator.org/construction/grout-calculator",
  "markdown": "https://www.acalculator.org/construction/grout-calculator.md",
  "kind": "function",
  "method": "Grout volume = area × (L + W) ÷ (L × W) × joint width × joint depth × (1 + waste ÷ 100); weight = volume × density; bags = weight ÷ bag size, rounded up.",
  "assumptions": [
    "Square-edged tiles laid in a grid, every joint the same width, filled to the joint depth (usually the tile thickness).",
    "The density is how much grout powder fills a unit of joint volume. 1.6 kg/L (about 100 lb/ft³) is a typical cement grout figure; for the best estimate use the coverage chart or data sheet of your grout.",
    "Waste is 10% by default, LATICRETE’s “10% rule”.",
    "Bags are 25 lb (11.3 kg) by default, a common size for cement grout."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "area": {
        "title": "Area to grout",
        "description": "The tiled floor or wall area.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "area",
        "exclusiveMinimum": 0,
        "maximum": 1000000
      },
      "tl": {
        "title": "Tile length",
        "description": "The long side of one tile.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 0.001,
        "maximum": 10
      },
      "tw": {
        "title": "Tile width",
        "description": "The short side of one tile.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 0.001,
        "maximum": 10
      },
      "joint": {
        "title": "Joint width",
        "description": "The gap between tiles: the spacer size.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 0.1
      },
      "depth": {
        "title": "Joint depth",
        "description": "How deep the grout goes: usually the tile thickness.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 0.1
      },
      "density": {
        "title": "Grout density",
        "description": "Pounds of grout powder that fill one cubic foot of joint. Check your grout’s coverage chart.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "density",
        "exclusiveMinimum": 0,
        "maximum": 5000
      },
      "waste": {
        "title": "Extra for waste",
        "description": "Extra grout for mixing, spills and clean-up; LATICRETE’s rule is at least 10%.",
        "type": "number",
        "x-unit": "percent",
        "minimum": 0,
        "maximum": 100
      },
      "bag": {
        "title": "Bag size",
        "description": "The weight of one bag of grout.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 0.1,
        "maximum": 1000
      }
    }
  },
  "outputs": {
    "pounds": {
      "label": "Grout (lb)",
      "description": "The grout powder to buy, in pounds, with the waste allowance.",
      "format": "number"
    },
    "kilograms": {
      "label": "Grout (kg)",
      "description": "The same weight in kilograms.",
      "format": "number"
    },
    "bags": {
      "label": "Bags to buy",
      "description": "The weight ÷ the bag size, rounded up.",
      "format": "integer"
    },
    "liters": {
      "label": "Joint volume (L)",
      "description": "The volume of all the joints, with the waste allowance, in litres.",
      "format": "number"
    },
    "perArea": {
      "label": "Grout per 100 ft² (lb)",
      "description": "Pounds of grout for each 100 square feet, without waste.",
      "format": "number"
    },
    "perM2": {
      "label": "Grout per m² (kg)",
      "description": "Kilograms of grout for each square metre, without waste.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "area": 9.290304,
      "tl": 0.30479999999999996,
      "tw": 0.30479999999999996,
      "joint": 0.003175,
      "depth": 0.009524999999999999,
      "density": 1600,
      "waste": 10,
      "bag": 11.33980925
    },
    "outputs": {
      "pounds": 7.15320381601657,
      "kilograms": 3.244638672,
      "bags": 1,
      "liters": 2.02789917,
      "perArea": 6.502912560015064,
      "perM2": 0.3175
    },
    "text": "Buy 7.2 lb of grout; bags to buy: 1."
  },
  "examples": [
    {
      "given": {
        "area": 9.290304,
        "tl": 0.30479999999999996,
        "tw": 0.30479999999999996,
        "joint": 0.003175,
        "depth": 0.009524999999999999,
        "density": 1600,
        "waste": 0,
        "bag": 11.33980925
      },
      "expect": {
        "liters": 1.8435447,
        "kilograms": 2.94967152,
        "pounds": 6.502912560015064,
        "perArea": 6.502912560015064,
        "bags": 1
      },
      "source": "Mapei group (Adesital), Grouts calculator (consumption from the volume to fill and the product density; inputs tile length, width, thickness and joint width). https://cms.mapei.com/adesital/en/product-calculator/grouts-calculator/; hand calculation in content.mdx: (12 + 12) ÷ 144 × 0.125 × 0.375 = 0.0078125 in of joint per in² of surface; × 14,400 in² = 112.5 in³ = 1.8435 L; × 1.6 kg/L = 2.95 kg = 6.5 lb"
    },
    {
      "given": {
        "area": 10,
        "tl": 0.3,
        "tw": 0.6,
        "joint": 0.003,
        "depth": 0.01,
        "density": 1600,
        "waste": 10,
        "bag": 5
      },
      "expect": {
        "perM2": 0.24,
        "kilograms": 2.64,
        "liters": 1.65,
        "bags": 1
      },
      "source": "LATICRETE, Mastering Grout Calculation: The Power of the Grout Calculator (add at least 10% for waste). https://www.laticrete.com/blog/2023/october/the-power-of-the-grout-calculator; hand calculation in content.mdx: (300 + 600) ÷ (300 × 600) × 3 × 10 × 1.6 = 0.24 kg/m²; × 10 × 1.1 = 2.64 kg"
    },
    {
      "given": {
        "area": 37.161216,
        "tl": 0.0508,
        "tw": 0.0508,
        "joint": 0.003175,
        "depth": 0.00635,
        "density": 1601.8463373960142,
        "waste": 10,
        "bag": 11.33980925
      },
      "expect": {
        "pounds": 114.58333333333333,
        "bags": 5
      },
      "source": "LATICRETE, Cement Grouts FAQ (25 lb bags of sanded and unsanded grout). https://www.laticrete.com/support-and-training/downloads-and-faq/faqs/planning-a-job/cement-grouts; hand calculation in content.mdx: (2 + 2) ÷ 4 × 0.125 × 0.25 = 0.03125 in; × 400 × 144 in² = 1,800 in³ × 1.1 = 1,980 in³ = 1.1458 ft³ × 100 lb/ft³ = 114.58 lb ÷ 25 = 4.58, so 5 bags"
    }
  ],
  "sources": [
    "Mapei group (Adesital), Grouts calculator (consumption from the volume to fill and the product density; inputs tile length, width and thickness, joint width and area; results are estimates). https://cms.mapei.com/adesital/en/product-calculator/grouts-calculator/ (retrieved 2026-10-01)",
    "LATICRETE, Mastering Grout Calculation: The Power of the Grout Calculator (tile size, joint width and depth, and area; add at least 10% for waste). https://www.laticrete.com/blog/2023/october/the-power-of-the-grout-calculator (retrieved 2026-10-01)",
    "LATICRETE, Cement Grouts FAQ (grout coverage is approximate; 25 lb (11.3 kg) bags). https://www.laticrete.com/support-and-training/downloads-and-faq/faqs/planning-a-job/cement-grouts (retrieved 2026-10-01)",
    "NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement: 1 in = 2.54 cm; 1 lb = 0.45359237 kg; 1 ft³ = 0.028316846592 m³. https://www.nist.gov/document/2026-nist-handbook-44-appendix-c (retrieved 2026-10-01)"
  ],
  "related": [
    "square-footage",
    "concrete",
    "drywall"
  ],
  "changelog": []
}