Maintenance IV Fluid Rate (4-2-1 Rule) — Free Online Calculator
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Maintenance Fluid Rate
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Daily Maintenance Volume
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About This Calculator
The 4-2-1 rule (Holliday-Segar method) is the standard method for calculating maintenance intravenous fluid requirements. It estimates the hourly fluid rate needed to replace normal daily fluid losses from metabolism, respiration, and urinary output. This is the baseline rate; additional fluids may be needed for ongoing losses (e.g., fever, burns, surgical drains).
Formula
Interpretation
| Weight Range | Rate | Example |
|---|---|---|
| 0 – 10 kg | 4 mL/kg/hr | 8 kg → 32 mL/hr |
| 11 – 20 kg | 40 + 2 mL/kg/hr | 15 kg → 50 mL/hr |
| > 20 kg | 60 + 1 mL/kg/hr | 70 kg → 110 mL/hr |
Frequently Asked Questions
What is the 4-2-1 rule for maintenance IV fluids?
The Holliday-Segar 4-2-1 rule calculates hourly fluid requirements based on body weight: 4 mL/kg/hr for the first 10 kg, 2 mL/kg/hr for the next 10 kg (11–20 kg), and 1 mL/kg/hr for each additional kg above 20 kg.
What type of IV fluid is used for maintenance?
For adults, 5% dextrose in 0.45% normal saline (D5 1/2 NS) with 20 mEq/L KCl is a common maintenance fluid. Recent evidence supports isotonic solutions (e.g., Lactated Ringer's or PlasmaLyte) over hypotonic solutions to reduce the risk of hospital-acquired hyponatremia.
When should maintenance IV fluids be adjusted?
Maintenance rates should be reduced in patients with heart failure, renal failure, or SIADH to prevent fluid overload. Rates should be increased in patients with fever (add ~10% per degree Celsius above 37°C), burns, or significant ongoing losses.
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⚠ Medical Disclaimer
This tool is for educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for clinical decisions.