{
  "id": "tidal-volume",
  "version": "d435bd2bdbac",
  "status": "published",
  "name": "Tidal Volume Calculator",
  "question": "What is the tidal volume by height?",
  "summary": "Works out predicted body weight from height and sex with the ARDS Network formula, and the tidal volume at a chosen mL per kg of predicted body weight, with the 4 to 8 mL/kg range.",
  "category": "health",
  "subcategory": "clinical",
  "url": "https://www.acalculator.org/health/tidal-volume-calculator",
  "markdown": "https://www.acalculator.org/health/tidal-volume-calculator.md",
  "kind": "function",
  "method": "PBW (kg) = 50 + 0.91 × (height cm − 152.4) for men, 45.5 + 0.91 × (height cm − 152.4) for women. Tidal volume (mL) = mL/kg × PBW.",
  "assumptions": [
    "Predicted body weight comes from height and sex only; actual weight is not used.",
    "The ARDS Network trial was in adults with acute lung injury or ARDS on a ventilator. The page shows the arithmetic; it does not set a ventilator.",
    "Values are worked from the exact typed height and rounded once: PBW to 1 decimal and volumes to the nearest mL, halves up."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "sex": {
        "title": "Sex",
        "description": "Sex, which sets the formula: 50 kg (male) or 45.5 kg (female) at 152.4 cm.",
        "type": "string",
        "enum": [
          "male",
          "female"
        ]
      },
      "height": {
        "title": "Height",
        "description": "Height, from 124 cm (4 ft 0.8 in) to 250 cm.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 1.24,
        "maximum": 2.5
      },
      "mlkg": {
        "title": "Tidal volume (mL/kg)",
        "description": "Millilitres per kg of predicted body weight, from 4 to 8. The ARDS Network trial started at 6.",
        "type": "number",
        "minimum": 4,
        "maximum": 8
      }
    }
  },
  "outputs": {
    "tidal": {
      "label": "Tidal volume",
      "description": "mL per kg × predicted body weight, to the nearest mL.",
      "format": "number"
    },
    "pbw": {
      "label": "Predicted body weight (kg)",
      "description": "50 (male) or 45.5 (female) + 0.91 × (height in cm − 152.4), to 1 decimal.",
      "format": "number"
    },
    "low": {
      "label": "At 4 mL/kg",
      "description": "The low end of the 4 to 8 mL/kg range, to the nearest mL.",
      "format": "number"
    },
    "high": {
      "label": "At 8 mL/kg",
      "description": "The high end of the 4 to 8 mL/kg range, to the nearest mL.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "sex": "male",
      "height": "5ft10in",
      "mlkg": 6
    },
    "outputs": {
      "tidal": 438.684,
      "pbw": 73.114,
      "low": 292.456,
      "high": 584.912
    },
    "text": "At 6 mL/kg, a predicted body weight of 73.1 kg gives a tidal volume of 439 mL."
  },
  "examples": [
    {
      "given": {
        "sex": "male",
        "height": 1.778,
        "mlkg": 6
      },
      "expect": {
        "pbw": 73.114,
        "tidal": 438.684,
        "low": 292.456,
        "high": 584.912
      },
      "source": "ARDS Network 2000: PBW = 50 + 0.91 × (177.8 − 152.4) = 73.114 kg; 6 × 73.114 = 438.7 mL (hand calculation in content.mdx)"
    },
    {
      "given": {
        "sex": "female",
        "height": 1.65,
        "mlkg": 6
      },
      "expect": {
        "pbw": 56.966,
        "tidal": 341.796
      },
      "source": "ARDS Network 2000: PBW = 45.5 + 0.91 × (165 − 152.4) = 56.966 kg; × 6 = 341.8 mL (hand calculation)"
    },
    {
      "given": {
        "sex": "male",
        "height": 1.524,
        "mlkg": 8
      },
      "expect": {
        "pbw": 50,
        "tidal": 400,
        "low": 200,
        "high": 400
      },
      "source": "ARDS Network 2000: PBW = 50 kg at 152.4 cm; 8 × 50 = 400 mL (hand calculation)"
    },
    {
      "given": {
        "sex": "female",
        "height": 1.524,
        "mlkg": 4
      },
      "expect": {
        "pbw": 45.5,
        "tidal": 182
      },
      "source": "ARDS Network 2000: PBW = 45.5 kg at 152.4 cm; 4 × 45.5 = 182 mL (hand calculation)"
    },
    {
      "given": {
        "sex": "male",
        "height": 1.85,
        "mlkg": 6.5
      },
      "expect": {
        "pbw": 79.666,
        "tidal": 517.829
      },
      "source": "PBW = 50 + 0.91 × 32.6 = 79.666 kg; 6.5 × 79.666 = 517.829 mL (hand calculation)"
    }
  ],
  "sources": [
    "Acute Respiratory Distress Syndrome Network. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342(18):1301-1308. https://doi.org/10.1056/NEJM200005043421801 (retrieved 2026-10-05)",
    "NHLBI ARDS Network. Tools: predicted body weight formulas and tables. http://www.ardsnet.org/tools.shtml (retrieved 2026-10-05)",
    "Martin DC, Richards GN. Predicted body weight relationships for protective ventilation: unisex proposals from pre-term through to adult. BMC Pulm Med. 2017;17:85. https://doi.org/10.1186/s12890-017-0427-1 (retrieved 2026-10-05)"
  ],
  "related": [],
  "changelog": [
    {
      "date": "2026-10-05",
      "note": "Published after this site's editorial review against the cited sources (no clinician review); the page notices say so."
    }
  ]
}