Maintenance Fluids Calculator
Calculate pediatric and adult IV maintenance fluid rates using the 4-2-1 Rule (Holliday-Segar Method).
What are Maintenance Fluids?
Maintenance fluids are intravenous (IV) liquids administered to patients who cannot maintain adequate oral intake. The goal is to replace the normal physiological loss of water and electrolytes from the skin, lungs, feces, and urine. This calculator utilizes the Holliday-Segar Method, commonly known as the "4-2-1 Rule," which has been the clinical standard since 1957.
Understanding the 4-2-1 Rule
The 4-2-1 rule is a simplified way to calculate the hourly rate of IV fluids based on a patient's weight in kilograms:
- 0 – 10 kg: 4 mL/kg/hr
- 11 – 20 kg: 40 mL/hr + 2 mL/kg/hr for every kg above 10 kg
- > 20 kg: 60 mL/hr + 1 mL/kg/hr for every kg above 20 kg
Calculation Example
If a child weighs 25 kg, the calculation is performed as follows:
- First 10 kg: 10 kg × 4 mL = 40 mL/hr
- Next 10 kg (11-20kg): 10 kg × 2 mL = 20 mL/hr
- Remaining weight (25-20kg): 5 kg × 1 mL = 5 mL/hr
- Total Hourly Rate: 40 + 20 + 5 = 65 mL/hr
Maintenance Fluid Requirements Table (Daily)
| Body Weight | Fluid Per Day (24 Hours) |
|---|---|
| First 10 kg | 100 mL/kg |
| Next 10 kg (11-20 kg) | 1,000 mL + 50 mL/kg for each kg > 10 |
| Each kg > 20 kg | 1,500 mL + 20 mL/kg for each kg > 20 |
Clinical Considerations
While the 4-2-1 rule is widely used, clinicians must adjust fluid rates based on the patient's specific condition. Factors such as fever (which increases fluid loss by roughly 12% per degree Celsius), surgical trauma, renal failure, or heart failure may require restricted or increased fluid administration. Always consult with a licensed medical professional for clinical decision-making.