{
  "slug": "maintenance-fluid-rate",
  "title": "Maintenance IV Fluid Rate Calculator (Holliday-Segar)",
  "heading": "Maintenance Fluid Rate Calculator",
  "category": "fitness-health",
  "url": "https://www.revenuelab.fyi/toolbox/maintenance-fluid-rate",
  "summary": "Hourly maintenance fluid needs from weight using the 4-2-1 rule.",
  "description": "The Holliday-Segar method, commonly remembered as the \"4-2-1 rule,\" estimates baseline maintenance fluid needs from body weight alone: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr for every kilogram after that. It was originally derived from caloric expenditure in children but is used across pediatrics and adults as a simple starting point for patients who are NPO or otherwise not meeting fluid needs orally, absent other losses. It assumes normal renal function, no fever, no significant ongoing losses (vomiting, diarrhea, drains, burns), and euvolemia at baseline — none of which is guaranteed in a sick patient, so this number is a starting point that must be adjusted for fever (roughly +10-12% per degree C above 37.5), ongoing losses, or third-spacing. In adults, many clinicians simplify to roughly 25-30 mL/kg/day for maintenance rather than the full stepwise Holliday-Segar calculation, and this tool shows both. This tool is for education and workflow support only — not medical advice. Always verify results with a clinician and use clinical judgment alongside your institution's protocols.",
  "formula": "4 mL/kg/hr for first 10kg + 2 mL/kg/hr for next 10kg + 1 mL/kg/hr for remainder; adult simplified estimate: 25-30 mL/kg/day.",
  "dateModified": "2026-09-30",
  "run_url": "https://www.revenuelab.fyi/api/public/calc?tool=maintenance-fluid-rate",
  "inputs": [
    {
      "id": "weight",
      "label": "Weight",
      "kind": "number",
      "hint": null,
      "default": 22,
      "unit": "kg",
      "min": 1,
      "max": 200
    },
    {
      "id": "feverC",
      "label": "Temperature above 37.5°C (0 if afebrile)",
      "kind": "number",
      "hint": null,
      "default": 0,
      "unit": "°C over",
      "min": 0,
      "max": 5
    }
  ],
  "outputs": [
    {
      "id": "rate",
      "label": "Hourly maintenance rate",
      "format": "decimal",
      "hint": null,
      "primary": true
    },
    {
      "id": "dailyVolume",
      "label": "24-hour maintenance volume",
      "format": "number",
      "hint": null,
      "primary": false
    },
    {
      "id": "baseRate",
      "label": "Base rate before fever adjustment",
      "format": "decimal",
      "hint": null,
      "primary": false
    },
    {
      "id": "adultSimplified",
      "label": "Adult simplified estimate (mL/day)",
      "format": "number",
      "hint": null,
      "primary": false
    }
  ],
  "worked_example": {
    "inputs": [
      "Weight: 22 kg",
      "Temperature above 37.5°C (0 if afebrile): 0 °C over"
    ],
    "outputs": [
      "Hourly maintenance rate: 62",
      "24-hour maintenance volume: 1,488",
      "Base rate before fever adjustment: 62",
      "Adult simplified estimate (mL/day): 605"
    ]
  },
  "how_to": {
    "title": "How to use this",
    "steps": [
      "Enter weight (kg).",
      "Enter temperature above 37.5°c (0 if afebrile) (°C over).",
      "Read your hourly maintenance rate on the right — it updates as you type.",
      "Hit Share to keep the scenario or send it to someone."
    ]
  },
  "scenarios": [
    {
      "name": "Conservative",
      "description": "Lower-end numbers — what if things land soft?",
      "values": {
        "weight": 22,
        "feverC": 0
      }
    },
    {
      "name": "Typical",
      "description": "Defaults — the most common real-world setup.",
      "values": {
        "weight": 22,
        "feverC": 0
      }
    },
    {
      "name": "Ambitious",
      "description": "Higher-end numbers — what if things really pop?",
      "values": {
        "weight": 22,
        "feverC": 0
      }
    }
  ],
  "limitations": [
    "Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.",
    "Results do not account for medical conditions, medication, or pregnancy.",
    "Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it."
  ],
  "faq": [
    {
      "q": "Does this account for dehydration or ongoing losses?",
      "a": "No. This is baseline maintenance only, assuming a euvolemic patient with no ongoing abnormal losses. Dehydration deficits, diarrhea, vomiting, NG suction, drain output, and burns all need to be added separately and are typically replaced over and above the calculated maintenance rate."
    },
    {
      "q": "Why does fever increase fluid needs?",
      "a": "Fever increases insensible losses through increased respiratory rate and sweating, roughly by 10-12% per degree Celsius above normal. This calculator applies a 10% per degree adjustment as a reasonable working estimate, but real replacement should be guided by ongoing clinical assessment, not the fever adjustment alone."
    },
    {
      "q": "Is Holliday-Segar still used in adults?",
      "a": "Less commonly for adults, where a simpler 25-30 mL/kg/day estimate is often used directly, shown here as the adult simplified figure. Holliday-Segar's stepwise method remains standard in pediatrics, where weight-based caloric-expenditure logic more directly applies."
    },
    {
      "q": "What about patients with heart failure or renal failure?",
      "a": "Maintenance fluid calculations assume normal cardiac and renal function. In heart failure or renal failure, fluid administration is typically restricted well below calculated maintenance and guided by volume status, urine output, and renal function rather than this formula."
    }
  ],
  "related": [
    "https://www.revenuelab.fyi/toolbox/ng-tube-fluid-replacement",
    "https://www.revenuelab.fyi/toolbox/creatinine-clearance-cockcroft-gault",
    "https://www.revenuelab.fyi/toolbox/shock-index"
  ],
  "license": "CC-BY-4.0",
  "citation": "RevenueLab — Maintenance IV Fluid Rate Calculator (Holliday-Segar) (https://www.revenuelab.fyi/toolbox/maintenance-fluid-rate)"
}