In pediatric medicine, fluid management and drug delivery are significantly more complex than in adult care. Because children have smaller total body water volumes and higher metabolic rates, even small errors in calculation can lead to fluid overload or toxicity. This calculator utilizes two primary clinical standards: the Holliday-Segar method (4-2-1 rule) and weight-based dosage calculations.
The 4-2-1 Rule for Maintenance Fluids
The 4-2-1 rule is the clinical gold standard for determining hourly maintenance fluid requirements for pediatric patients based on their body weight. The calculation is broken down as follows:
First 10 kg: 4 mL/kg/hr
Next 10 kg (11-20 kg): 2 mL/kg/hr
Each kg above 20 kg: 1 mL/kg/hr
Example Calculation (4-2-1 Rule)
If a child weighs 25 kg:
First 10 kg: 10 × 4 = 40 mL/hr
Next 10 kg: 10 × 2 = 20 mL/hr
Remaining 5 kg: 5 × 1 = 5 mL/hr
Total Rate: 40 + 20 + 5 = 65 mL/hr
Calculating Dosage-to-Rate (mcg/kg/min)
Critical care medications (like dopamine or epinephrine) are often prescribed in micrograms per kilogram per minute (mcg/kg/min). To convert this to a pump setting (mL/hr), the concentration of the drug in the IV bag must be known. The formula used is:
Standard isotonic fluid bolus for pediatric resuscitation.
Medical Disclaimer: This calculator is for educational purposes only. It is not a substitute for clinical judgment. Always double-check calculations with a second provider or hospital protocols before administering fluids or medication to a pediatric patient.
function calculateMaintenance() {
var weight = parseFloat(document.getElementById('maint_weight').value);
var hourlyRate = 0;
if (isNaN(weight) || weight <= 0) {
alert("Please enter a valid weight.");
return;
}
if (weight <= 10) {
hourlyRate = weight * 4;
} else if (weight <= 20) {
hourlyRate = 40 + ((weight – 10) * 2);
} else {
hourlyRate = 60 + ((weight – 20) * 1);
}
var dailyRate = hourlyRate * 24;
document.getElementById('hourly_rate_val').innerText = hourlyRate.toFixed(1);
document.getElementById('daily_rate_val').innerText = dailyRate.toFixed(1);
document.getElementById('maint_result').style.display = 'block';
}
function calculateDosageRate() {
var weight = parseFloat(document.getElementById('dose_weight').value);
var dose = parseFloat(document.getElementById('target_dose').value);
var drugMg = parseFloat(document.getElementById('drug_amount').value);
var bagMl = parseFloat(document.getElementById('bag_volume').value);
var dripFactor = parseFloat(document.getElementById('drip_factor').value);
if (isNaN(weight) || isNaN(dose) || isNaN(drugMg) || isNaN(bagMl)) {
alert("Please fill in all dosage fields with valid numbers.");
return;
}
// 1. Calculate concentration in mcg/mL
// Concentration = (mg * 1000) / mL
var concMcgMl = (drugMg * 1000) / bagMl;
// 2. Calculate infusion rate in mL/hr
// Rate (mL/hr) = (Dose * Weight * 60) / Concentration
var mlHr = (dose * weight * 60) / concMcgMl;
// 3. Calculate drip rate in gtt/min
// gtt/min = (mL/hr * dripFactor) / 60
var gttMin = (mlHr * dripFactor) / 60;
document.getElementById('infusion_ml_hr').innerText = mlHr.toFixed(2);
document.getElementById('infusion_gtt_min').innerText = gttMin.toFixed(1);
document.getElementById('drug_conc').innerText = concMcgMl.toFixed(2);
document.getElementById('dosage_result').style.display = 'block';
}