{
  "id": "coffee-ratio",
  "version": "058447606e81",
  "status": "published",
  "name": "Coffee Ratio Calculator",
  "question": "How much coffee for my water?",
  "summary": "Works out how much ground coffee to use for an amount of water, or how much water for your coffee, at a brew ratio such as 1:16, in grams, ounces, milliliters and cups.",
  "category": "food",
  "subcategory": "brewing",
  "url": "https://www.acalculator.org/food/coffee-ratio-calculator",
  "markdown": "https://www.acalculator.org/food/coffee-ratio-calculator.md",
  "kind": "function",
  "method": "For a 1:N ratio, coffee grams = water grams ÷ N and water grams = coffee grams × N, with 1 mL of water = 1 g. Strength = 1,000 ÷ N grams per liter.",
  "assumptions": [
    "The ratio is by weight, brewing water to dry ground coffee. Water is taken as 1 g per mL.",
    "The brewed coffee is less than the water you pour, because the grounds hold some back (about twice their weight)."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "from": {
        "title": "Start from",
        "description": "The water you will brew with, or the coffee you have.",
        "type": "string",
        "enum": [
          "water",
          "coffee"
        ]
      },
      "w": {
        "title": "Water",
        "description": "The brewing water.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "volume",
        "minimum": 0.000001,
        "maximum": 0.1
      },
      "c": {
        "title": "Ground coffee",
        "description": "The ground coffee you will use.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 0.000001,
        "maximum": 10
      },
      "r": {
        "title": "Ratio 1 :",
        "description": "Grams of water per gram of coffee: 16 means 1:16. Lower is stronger.",
        "type": "number",
        "minimum": 1,
        "maximum": 100
      }
    }
  },
  "outputs": {
    "result": {
      "label": "Brew",
      "description": "Coffee and water at your ratio, to 4 significant figures.",
      "format": "text"
    },
    "coffeeG": {
      "label": "Coffee (g)",
      "description": "Water grams ÷ ratio.",
      "format": "number"
    },
    "coffeeOz": {
      "label": "Coffee (oz)",
      "description": "The coffee in ounces.",
      "format": "number"
    },
    "waterML": {
      "label": "Water (mL or g)",
      "description": "Coffee grams × ratio; 1 mL of water weighs 1 g.",
      "format": "number"
    },
    "waterFloz": {
      "label": "Water (fl oz)",
      "description": "The water in US fluid ounces.",
      "format": "number"
    },
    "cups": {
      "label": "Water (8 fl oz cups)",
      "description": "The water in 8 fl oz cups.",
      "format": "number"
    },
    "strength": {
      "label": "Coffee per liter (g/L)",
      "description": "1,000 ÷ ratio grams of coffee per liter of water.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "from": "water",
      "w": "500 mL",
      "c": "30 g",
      "r": 16
    },
    "outputs": {
      "result": "31.25 g coffee to 500 g water",
      "coffeeG": 31.25,
      "coffeeOz": 1.1023113109243878,
      "waterML": 500,
      "waterFloz": 16.907011350921497,
      "cups": 2.113376418865187,
      "strength": 62.5
    },
    "text": "Use 31.25 g coffee to 500 g water."
  },
  "examples": [
    {
      "given": {
        "from": "water",
        "w": 0.001,
        "r": 18
      },
      "expect": {
        "coffeeG": 55.55555555555556,
        "strength": 55.55555555555556,
        "result": "55.56 g coffee to 1000 g water"
      },
      "source": "Wikipedia, Coffee preparation (brew ratios of water to coffee often 15–18:1 by mass; SCA 55 g of coffee per liter of water), https://en.wikipedia.org/wiki/Coffee_preparation (retrieved 2026-10-03); hand calculation in content.mdx: 1,000 g ÷ 18 = 55.56 g"
    },
    {
      "given": {
        "from": "water",
        "w": 0.0005,
        "r": 16
      },
      "expect": {
        "coffeeG": 31.25,
        "result": "31.25 g coffee to 500 g water"
      },
      "source": "Wikipedia, Coffee preparation (brew ratios of water to coffee often 15–18:1 by mass; SCA 55 g of coffee per liter of water), https://en.wikipedia.org/wiki/Coffee_preparation (retrieved 2026-10-03); hand calculation in content.mdx: 500 ÷ 16 = 31.25 g"
    },
    {
      "given": {
        "from": "coffee",
        "c": 0.02,
        "r": 15
      },
      "expect": {
        "waterML": 300,
        "waterFloz": 10.1442068105529,
        "cups": 1.2680258513191125
      },
      "source": "Wikipedia, Coffee preparation (brew ratios of water to coffee often 15–18:1 by mass; SCA 55 g of coffee per liter of water), https://en.wikipedia.org/wiki/Coffee_preparation (retrieved 2026-10-03); hand calculation in content.mdx: 20 × 15 = 300 g; 300 ÷ 29.5735295625 = 10.144 fl oz"
    }
  ],
  "sources": [
    "Wikipedia, Coffee preparation: preferred brew ratios of water to coffee often fall in the range of 15–18:1 by mass; the SCA standard of 55 g of coffee per liter of water; 7 g of grounds for a 25 mL espresso. Retrieved 2026-10-03. https://en.wikipedia.org/wiki/Coffee_preparation",
    "NIST Special Publication 811, Appendix B.8: 1 US fluid ounce = 2.957353 × 10⁻⁵ m³; 1 oz (mass) = 28.349523125 g. Retrieved 2026-10-03. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8"
  ],
  "related": [
    "recipe-scaler",
    "abv",
    "food-calorie"
  ],
  "changelog": []
}