{
  "id": "water-intake",
  "version": "516905881849",
  "status": "published",
  "name": "Water Intake Calculator",
  "question": "How much water to drink a day?",
  "summary": "Gives the daily Adequate Intake of water from the National Academies (Institute of Medicine, 2005) for an age and sex, and during pregnancy or breastfeeding: total water and the part from drinks, in litres, cups, and fluid ounces.",
  "category": "health",
  "subcategory": "nutrition",
  "url": "https://www.acalculator.org/health/water-intake-calculator",
  "markdown": "https://www.acalculator.org/health/water-intake-calculator.md",
  "kind": "function",
  "method": "Look up the Institute of Medicine Adequate Intake for the age, sex, and life stage: total water and the part from drinks, in litres per day; cups = litres ÷ 0.2365882365.",
  "assumptions": [
    "The intakes are the Institute of Medicine (2005) Adequate Intakes for healthy people, set from the median intakes of well-hydrated people in a US survey.",
    "Drinks include plain water and every other beverage, including coffee and tea; the rest of the total comes from food.",
    "People who are physically active or exposed to heat need more total water (IOM).",
    "Pregnancy and breastfeeding values apply to ages 14 to 50. This is general information, not medical advice."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "age": {
        "title": "Age",
        "description": "Your age in whole years, from 1.",
        "type": "integer",
        "minimum": 1,
        "maximum": 120
      },
      "sex": {
        "title": "Sex",
        "description": "Sex, which sets the intake from age 9.",
        "type": "string",
        "enum": [
          "male",
          "female"
        ]
      },
      "stage": {
        "title": "Pregnant or breastfeeding?",
        "description": "Pregnancy and breastfeeding have their own intakes, for ages 14 to 50.",
        "type": "string",
        "enum": [
          "none",
          "pregnant",
          "breastfeeding"
        ]
      }
    }
  },
  "outputs": {
    "drinks": {
      "label": "From drinks",
      "description": "Water to drink each day, including all beverages: the IOM figure for drinks.",
      "format": "quantity",
      "unit": "L"
    },
    "cups": {
      "label": "Cups of drinks",
      "description": "The water from drinks in US cups of 8 fluid ounces.",
      "format": "number"
    },
    "ounces": {
      "label": "Fluid ounces of drinks",
      "description": "The water from drinks in US fluid ounces.",
      "format": "quantity",
      "unit": "floz"
    },
    "total": {
      "label": "Total water",
      "description": "The Adequate Intake of total water per day: drinks plus water in food.",
      "format": "quantity",
      "unit": "L"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "age": 30,
      "sex": "female",
      "stage": "none"
    },
    "outputs": {
      "drinks": 0.0022,
      "cups": 9.298856243006826,
      "ounces": 0.0022,
      "total": 0.0027
    },
    "text": "Aim for about 2.2 L (9.3 cups) of drinks a day. With the water in food, that is 2.7 L of water in all."
  },
  "examples": [
    {
      "given": {
        "age": 30,
        "sex": "female",
        "stage": "none"
      },
      "expect": {
        "total": 0.0027,
        "drinks": 0.0022,
        "cups": 9.298856243006826
      },
      "source": "Institute of Medicine (2005), DRI for Water, chapter 4: women 19 to 30 years, 2.7 L/day total water, about 2.2 L (≈ 9 cups) from beverages"
    },
    {
      "given": {
        "age": 45,
        "sex": "male"
      },
      "expect": {
        "total": 0.0037,
        "drinks": 0.003,
        "cups": 12.680258513191124
      },
      "source": "Institute of Medicine (2005), chapter 4: men 31 to 50 years, 3.7 L/day total water, about 3.0 L (≈ 13 cups) from beverages"
    },
    {
      "given": {
        "age": 28,
        "sex": "female",
        "stage": "pregnant"
      },
      "expect": {
        "total": 0.003,
        "drinks": 0.0023
      },
      "source": "Institute of Medicine (2005), chapter 4: pregnancy, 3.0 L/day total water, about 2.3 L (≈ 10 cups) from beverages"
    },
    {
      "given": {
        "age": 25,
        "sex": "female",
        "stage": "breastfeeding"
      },
      "expect": {
        "total": 0.0038,
        "drinks": 0.0031
      },
      "source": "Institute of Medicine (2005), chapter 4: lactation, 3.8 L/day total water, about 3.1 L (≈ 13 cups) from beverages"
    },
    {
      "given": {
        "age": 15,
        "sex": "male"
      },
      "expect": {
        "total": 0.0033,
        "drinks": 0.0026
      },
      "source": "Institute of Medicine (2005), chapter 4: boys 14 to 18 years, 3.3 L/day total water, about 2.6 L from beverages"
    },
    {
      "given": {
        "age": 6,
        "sex": "female"
      },
      "expect": {
        "total": 0.0017,
        "drinks": 0.0012
      },
      "source": "Institute of Medicine (2005), chapter 4: children 4 to 8 years, 1.7 L/day total water, about 1.2 L from beverages"
    }
  ],
  "sources": [
    "Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: The National Academies Press, 2005, chapter 4 (Water) and Summary. doi:10.17226/10925. https://www.nationalacademies.org/read/10925/chapter/6",
    "National Academies of Sciences, Engineering, and Medicine. Report sets dietary intake levels for water, salt, and potassium to maintain health and reduce chronic disease risk (news release, February 11, 2004).",
    "Sawka MN, Burke LM, Eichner ER, et al. American College of Sports Medicine position stand: Exercise and fluid replacement. Medicine and Science in Sports and Exercise 2007;39:377–390. doi:10.1249/mss.0b013e31802ca597",
    "NIST SP 811 (2008), Appendix B: 1 US gallon = 3.785411784 L exactly; 1 cup = 1/16 gallon = 8 fluid ounces = 0.2365882365 L."
  ],
  "related": [
    "calories-burned-walking",
    "bmi"
  ],
  "changelog": []
}