Internal Medicine

Maintenance IV Fluids Calculator (4-2-1 Rule)

Maintenance IV Fluids Calculator (4-2-1 Rule)

Maintenance IV Fluids

Calculates hourly IV maintenance fluid rates based on the “4-2-1” rule for pediatric and adult patients.
Patient Weight
Enter weight in kilograms (kg)
0
mL / hour
Maintenance Rate
24-Hour Total: 0 mL
Weight SegmentRate Calculation
First 10 kg4 mL / kg / hr
10 – 20 kg+ 2 mL / kg / hr
Above 20 kg+ 1 mL / kg / hr
!
Obesity: Consider using Ideal Body Weight in obese patients to avoid fluid overload.
!
Clinical Status: This formula calculates volume only. Electrolyte composition (e.g., NaCl/Dextrose) must be tailored to the patient’s metabolic needs.
!
Contraindications: Be cautious in patients with renal failure, heart failure, or SIADH where restrictive fluid management may be required.
For clinical decision support only. Maintenance rates should be adjusted based on clinical judgment, dehydration, and ongoing losses.
References:
  • Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-832.
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Reviewed by ·
Semahattin Serkan Sezer MD

Pulmonologist and Intensive Care Specialist specializing in clinical informatics and the development of evidence-based decision support tools for healthcare professionals.