Pediatric Fluid Maintenance Calculator
Calculates the daily maintenance fluid requirement for a child using the Holliday-Segar method based on body weight. Commonly used by nurses and physicians when prescribing IV fluids or assessing hydration needs.
About this calculator
The Holliday-Segar method, published in 1957, is the standard approach to estimating daily maintenance fluid needs in children. It uses a three-tier weight-based formula: for the first 10 kg of body weight, allow 100 mL/kg/day; for the next 10 kg (10–20 kg), add 50 mL/kg/day; for every kilogram above 20 kg, add 20 mL/kg/day. Expressed as a formula: if weight ≤ 10 kg, Fluids = weight × 100; if weight ≤ 20 kg, Fluids = 1000 + (weight − 10) × 50; if weight > 20 kg, Fluids = 1500 + (weight − 20) × 20. These estimates reflect baseline insensible losses, urine output, and metabolic water needs. Adjustments are required for fever, burns, excessive sweating, or disease states that alter fluid balance.
How to use
Example: A child weighs 25 kg. Step 1 — Weight exceeds 20 kg, so use the third tier. Step 2 — Apply the formula: Fluids = 1500 + (25 − 20) × 20 = 1500 + 5 × 20 = 1500 + 100 = 1600 mL/day. Step 3 — To find an hourly IV rate, divide by 24: 1600 / 24 ≈ 66.7 mL/hour. For a 7 kg infant: Fluids = 7 × 100 = 700 mL/day (≈ 29 mL/hour). These figures represent maintenance needs only and do not include replacement for deficits or ongoing losses.
Frequently asked questions
What is the Holliday-Segar method for calculating pediatric fluid maintenance?
The Holliday-Segar method is a weight-based formula developed in 1957 that estimates a child's daily maintenance fluid requirements by dividing body weight into three segments. The first 10 kg accounts for 100 mL/kg/day, the second 10 kg (weights 10–20 kg) accounts for 50 mL/kg/day, and any weight above 20 kg accounts for 20 mL/kg/day. These tiers reflect decreasing metabolic water needs per unit mass as body size increases. The method is widely taught in medical and nursing training and remains the most commonly used bedside tool for initial IV fluid prescribing in children.
When should pediatric maintenance fluids be adjusted above or below the calculated amount?
The Holliday-Segar calculation provides a baseline estimate and must be modified in many clinical situations. Fever increases insensible water losses by roughly 10–12% per degree Celsius above 38°C, requiring upward adjustment. Conversely, children with conditions such as syndrome of inappropriate antidiuretic hormone secretion (SIADH), renal impairment, or cardiac failure may require fluid restriction well below the calculated maintenance. Post-operative patients and those with meningitis or head injury are sometimes managed with restricted volumes to reduce the risk of hyponatremia. Always reassess fluid balance regularly using clinical signs and laboratory values.
How do I convert a daily pediatric fluid maintenance volume to an hourly IV drip rate?
Divide the total daily maintenance volume in milliliters by 24 to obtain the hourly infusion rate. For example, if the daily requirement is 1600 mL, the hourly rate is 1600 ÷ 24 ≈ 67 mL/hour. A useful shortcut sometimes taught in pediatric training is the '4-2-1 rule': 4 mL/kg/hour for the first 10 kg, 2 mL/kg/hour for the next 10 kg, and 1 mL/kg/hour for each kg above 20 kg — this produces the same result as the daily Holliday-Segar calculation divided by 24. Always set infusion pumps accurately and reassess the rate as the child's condition changes.