Pediatric Fluid Calculator

The Holliday-Segar method, published in 1957, is the standard formula for calculating maintenance IV fluid requirements in children. It uses a stepped calculation based on body weight: 100 mL/kg/day for the first 10 kg, 50 mL/kg/day for the next 10 kg, and 20 mL/kg/day for each kilogram above 20 kg. This translates to the commonly used '4-2-1 rule' for hourly rates.

The 4-2-1 rule is the hourly equivalent of the Holliday-Segar formula: 4 mL/kg/hr for the first 10 kg of body weight, 2 mL/kg/hr for the next 10 kg, and 1 mL/kg/hr for each kilogram above 20 kg. It provides a quick bedside method to estimate maintenance fluid rates for children.

Reduced rates (typically 60–80% of standard maintenance) are recommended in clinical situations where fluid restriction is necessary, such as syndrome of inappropriate antidiuretic hormone secretion (SIADH), bacterial meningitis, post-operative states, traumatic brain injury, or severe respiratory distress. Always follow institutional guidelines and physician judgment.

The Holliday-Segar method is generally validated for children weighing more than 3.5–4 kg and older infants. For neonates, especially premature infants, fluid requirements differ significantly based on gestational age, insensible losses, and clinical condition. Neonatal fluid management should follow specialized neonatal protocols under direct physician supervision.

Isotonic fluids such as 0.9% NaCl with 5% dextrose (D5NS) or 0.9% NaCl with dextrose and potassium are commonly used for pediatric maintenance therapy. The choice of fluid composition should be made by the treating physician based on the child's electrolyte status, age, and clinical condition. This calculator only estimates the volume, not the fluid type.

This calculator applies the standard Holliday-Segar formula, which is widely accepted in clinical practice. However, maintenance fluid needs can vary based on fever, dehydration, burns, renal function, and other factors. It is intended as a clinical decision-support tool and should always be reviewed by a licensed healthcare professional before administration.

Select 'Pounds (lbs)' from the weight unit dropdown and the calculator will automatically convert the value to kilograms before applying the formula. The standard conversion is 1 lb = 0.4536 kg. The exact weight in kilograms used for the calculation is displayed in the results.

The calculator supports weights up to 100 kg. For patients above 20 kg, the formula continues to add 20 mL/kg/day (or 1 mL/kg/hr) for each additional kilogram. In adolescents and larger children, the calculated maintenance rate typically does not exceed typical adult maintenance volumes of around 2000–2500 mL/day.