{
  "id": "strike-water",
  "version": "806b4cabdb10",
  "status": "published",
  "name": "Strike Water Calculator",
  "question": "How hot should my strike water be?",
  "summary": "Works out the strike water temperature and volume for an all-grain mash from the grain weight, the water-to-grain ratio, the grain temperature and the target mash temperature (Palmer’s infusion equation).",
  "category": "food",
  "subcategory": "brewing",
  "url": "https://www.acalculator.org/food/strike-water-calculator",
  "markdown": "https://www.acalculator.org/food/strike-water-calculator.md",
  "kind": "function",
  "method": "Tw = (c ÷ r)(T2 − T1) + T2, c = 0.2 with qt/lb and °F or 0.41 with L/kg and °C; volume = r × grain weight.",
  "assumptions": [
    "The mash tun is preheated, so it takes no heat from the water; a cold tun needs hotter water.",
    "0.2 and 0.41 are the grain’s heat capacity relative to water in each set of units; the two systems can differ by a few tenths of a degree.",
    "All the strike water goes in at once (a single infusion)."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "units": {
        "title": "Units",
        "description": "US (pounds, quarts, °F) or metric (kilograms, liters, °C).",
        "type": "string",
        "enum": [
          "us",
          "metric"
        ]
      },
      "g": {
        "title": "Grain weight (lb)",
        "description": "The weight of the grain bill, in pounds.",
        "type": "number",
        "minimum": 0.01,
        "maximum": 10000
      },
      "r": {
        "title": "Water to grain (qt/lb)",
        "description": "Quarts of strike water per pound of grain.",
        "type": "number",
        "minimum": 0.1,
        "maximum": 10
      },
      "t1": {
        "title": "Grain temperature (°F)",
        "description": "The temperature of the grain, often room temperature.",
        "type": "number",
        "minimum": -40,
        "maximum": 200
      },
      "t2": {
        "title": "Target mash temperature (°F)",
        "description": "The mash temperature you want.",
        "type": "number",
        "minimum": 32,
        "maximum": 212
      },
      "gkg": {
        "title": "Grain weight (kg)",
        "description": "The weight of the grain bill, in kilograms.",
        "type": "number",
        "minimum": 0.01,
        "maximum": 5000
      },
      "rl": {
        "title": "Water to grain (L/kg)",
        "description": "Liters of strike water per kilogram of grain.",
        "type": "number",
        "minimum": 0.1,
        "maximum": 20
      },
      "t1c": {
        "title": "Grain temperature (°C)",
        "description": "The temperature of the grain, often room temperature.",
        "type": "number",
        "minimum": -40,
        "maximum": 93
      },
      "t2c": {
        "title": "Target mash temperature (°C)",
        "description": "The mash temperature you want.",
        "type": "number",
        "minimum": 0,
        "maximum": 100
      }
    }
  },
  "outputs": {
    "strike": {
      "label": "Strike water temperature",
      "description": "Tw = (c ÷ r)(T2 − T1) + T2, in °F (US) or °C (metric).",
      "format": "number"
    },
    "volume": {
      "label": "Strike water volume",
      "description": "Ratio × grain weight, in quarts (US) or liters (metric).",
      "format": "number"
    },
    "gallons": {
      "label": "Strike water (US gallons)",
      "description": "The volume in US gallons (4 quarts), for the US units.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "units": "us",
      "g": 10,
      "r": 1.25,
      "t1": 68,
      "t2": 152,
      "gkg": 5,
      "rl": 2.5,
      "t1c": 18,
      "t2c": 67
    },
    "outputs": {
      "strike": 165.44,
      "volume": 12.5,
      "gallons": 3.125
    },
    "text": "Heat the strike water to 165.4 degrees (°F with US units, °C with metric)."
  },
  "examples": [
    {
      "given": {
        "units": "us",
        "g": 10,
        "r": 1.25,
        "t1": 68,
        "t2": 152
      },
      "expect": {
        "strike": 165.44,
        "volume": 12.5,
        "gallons": 3.125
      },
      "source": "hand calculation in content.mdx: (0.2 ÷ 1.25)(152 − 68) + 152 = 0.16 × 84 + 152 = 165.44 °F; John Palmer, How to Brew, online edition, Calculating Strike Water Temperature (Tw = (0.2 ÷ r)(T2 − T1) + T2; r in qt/lb, °F), http://howtobrew.com/book/section-3/how-the-mash-works/calculating-strike-water-temperature"
    },
    {
      "given": {
        "units": "metric",
        "gkg": 5,
        "rl": 2.5,
        "t1c": 18,
        "t2c": 67
      },
      "expect": {
        "strike": 75.036,
        "volume": 12.5
      },
      "source": "Home Brew Answers, Calculating Strike Water Temperature For Mashing (Tw = (0.41 ÷ R)(T2 − T1) + T2 with L/kg and °C; example (0.41 ÷ 2.5) × (67 − 18) + 67 = 75 °C), https://homebrewanswers.com/document/calculating-strike-water-temperature-for-mashing/ (shown there as 75 °C); hand calculation: 0.164 × 49 + 67 = 75.036"
    },
    {
      "given": {
        "units": "us",
        "g": 12,
        "r": 1.5,
        "t1": 60,
        "t2": 154
      },
      "expect": {
        "strike": 166.53333333333333,
        "volume": 18,
        "gallons": 4.5
      },
      "source": "hand calculation in content.mdx: (0.2 ÷ 1.5) × 94 + 154 = 18.8 ÷ 1.5 + 154 = 166.5333 °F; Python 3: Fraction; John Palmer, How to Brew, online edition, Calculating Strike Water Temperature (Tw = (0.2 ÷ r)(T2 − T1) + T2; r in qt/lb, °F), http://howtobrew.com/book/section-3/how-the-mash-works/calculating-strike-water-temperature"
    }
  ],
  "sources": [
    "John Palmer, How to Brew, online edition, Calculating Strike Water Temperature (initial infusion equation Tw = (0.2 ÷ r)(T2 − T1) + T2; r in quarts per pound, temperatures in °F). http://howtobrew.com/book/section-3/how-the-mash-works/calculating-strike-water-temperature (the site’s security certificate had expired when checked on 2026-10-19; the equation matches the Home Brew Answers page below)",
    "Home Brew Answers, Calculating Strike Water Temperature For Mashing (metric form Tw = (0.41 ÷ R)(T2 − T1) + T2 with R in L/kg and °C; example (0.41 ÷ 2.5) × (67 − 18) + 67 = 75 °C). https://homebrewanswers.com/document/calculating-strike-water-temperature-for-mashing/ (retrieved 2026-10-19)"
  ],
  "related": [
    "abv",
    "brine"
  ],
  "changelog": []
}