Pediatric Fluid Requirements Calculator
Calculates a child's daily fluid requirement in milliliters using the Holliday-Segar method, adjusted for activity level and clinical conditions like fever or dehydration. Ideal for parents, nurses, and pediatric caregivers.
About this calculator
This calculator uses the Holliday-Segar method, the clinical standard for estimating daily maintenance fluid needs in children. The base formula is: for weight ≤ 10 kg: fluid (mL) = weight × 100; for 10–20 kg: fluid = 1000 + (weight − 10) × 50; for weight > 20 kg: fluid = 1500 + (weight − 20) × 20. This gives the maintenance fluid volume assuming normal conditions. The result is then multiplied by an activity factor (0.9 for low activity, 1.0 for normal, 1.2 for high activity) and a clinical condition factor (1.15 for fever, 1.25 for dehydration, 0.8 for fluid-restricted states, 1.0 for normal). These adjustments reflect the increased insensible losses during illness or exercise and reduced requirements when fluids must be restricted.
How to use
Consider a 15 kg child with a fever and normal activity. Base fluid using the middle tier: 1000 + (15 − 10) × 50 = 1000 + 250 = 1,250 mL. Activity factor (normal) = 1.0; fever factor = 1.15. Total: 1,250 × 1.0 × 1.15 = 1,438 mL/day. Enter weight (15 kg), activity level (normal), and clinical condition (fever) to get this result. This tells a caregiver to ensure the child drinks approximately 1,438 mL of fluids over 24 hours.
Frequently asked questions
How much water should a child drink per day by weight?
The Holliday-Segar method provides a practical weight-based answer: 100 mL/kg for the first 10 kg, 50 mL/kg for the next 10 kg, and 20 mL/kg for every kilogram above 20 kg. For example, a 25 kg child needs approximately 1,600 mL per day under normal conditions. These are maintenance fluid needs and cover water from all sources including food. Additional fluids are needed during illness, heat, or vigorous physical activity.
Why does fever increase a child's fluid requirements?
Fever raises body temperature, which increases metabolic rate and insensible water losses through sweating and faster breathing. For every 1°C rise in temperature above normal, fluid losses increase by roughly 10–12%. This calculator applies a 15% increase for fever, reflecting moderate febrile illness. Ensuring adequate hydration during fever helps prevent dehydration, supports immune function, and aids temperature regulation. If a child cannot maintain oral intake during fever, seek medical advice promptly.
When should I use the pediatric fluid calculator versus consulting a doctor?
This calculator is appropriate for estimating healthy daily fluid intake goals in well or mildly unwell children at home. It helps parents understand whether a child is drinking enough during routine illnesses or hot weather. It is not a substitute for clinical assessment when a child shows signs of significant dehydration such as no urine output, dry mouth, sunken eyes, or lethargy. In those cases, intravenous fluids managed by a healthcare professional may be necessary.