*Calculation based on the standard Holliday-Segar (4-2-1) method. Verify all calculations clinically.
How to Calculate Pediatric IV Fluid Rates
Determining the correct maintenance fluid rate for pediatric patients is a critical skill in clinical settings. Unlike adults, where standard rates are often applied, pediatric fluid management requires precise calculation based on the child's weight to prevent dehydration or fluid overload.
This calculator utilizes the Holliday-Segar method, also widely known as the 4-2-1 Rule. This formula is the gold standard for estimating maintenance fluid requirements in children.
Understanding the 4-2-1 Rule
The 4-2-1 rule breaks down the fluid requirement calculation into weight categories. It calculates the hourly infusion rate (mL/hr) based on the first 10 kg, the second 10 kg, and any remaining weight.
Weight Category
Calculation Rule
First 0 – 10 kg
4 mL per kg per hour
Next 10 – 20 kg
Add 2 mL per kg per hour
Above 20 kg
Add 1 mL per kg per hour
Calculation Examples
Example 1: 8 kg Infant
Since the weight is under 10 kg, we simply multiply by 4.
Math: 8 kg × 4 mL/kg/hr = 32 mL/hr
Example 2: 15 kg Toddler
This child crosses the first threshold. We calculate the first 10 kg separately from the remaining 5 kg.
First 10 kg: 10 × 4 = 40 mL/hr
Remaining 5 kg: 5 × 2 = 10 mL/hr
Total: 40 + 10 = 50 mL/hr
Example 3: 25 kg Child
This child crosses both thresholds.
First 10 kg: 10 × 4 = 40 mL/hr
Second 10 kg: 10 × 2 = 20 mL/hr
Remaining 5 kg: 5 × 1 = 5 mL/hr
Total: 40 + 20 + 5 = 65 mL/hr
Daily Volume vs. Hourly Rate
While modern infusion pumps are programmed in mL/hr, it is also useful to know the total daily volume (mL/day) to ensure adequate fluid stock.
Hourly Rate: Calculated via the 4-2-1 rule.
Daily Volume: Hourly Rate × 24 hours.
Alternatively, the daily volume can be calculated using the 100-50-20 rule (100 mL/kg for the first 10kg, 50 mL/kg for the next 10kg, etc.), which yields the mathematically equivalent result.
Clinical Considerations
The rates calculated here represent maintenance fluid needs. They do not account for: