Pediatric Fluid Calculator

This calculator applies the Holliday-Segar formula, the standard bedside method for estimating pediatric maintenance IV fluid requirements from body weight alone. Published by Holliday and Segar in 1957 and still the basis for maintenance fluid orders in pediatric practice today, the formula is tiered rather than a flat per-kilogram rate: it allots 100 mL/kg/day for the first 10 kg of Weight, 50 mL/kg/day for the next 10 kg (10-20 kg), and only 20 mL/kg/day for every kilogram above 20 kg, up to a 40 kg ceiling. That tiering reflects a real physiological pattern -- metabolic rate, and therefore fluid turnover, rises more slowly than body mass as a child grows -- so each additional kilogram above 20 kg adds proportionally less to Daily Volume than a kilogram in the first tier did. The calculator sums the three band contributions (First 10 kg Contribution, Next 10 kg Contribution, Above 20 kg Contribution) into Daily Volume, then divides by 24 to produce Hourly Rate for setting an IV pump. Holliday-Segar is a PEDIATRIC formula and is not meant to be extrapolated onto an adult-sized body: real practice typically caps weight-based dosing by this method around 20-40 kg, switching to standard adult maintenance fluid dosing above that.

This calculator caps its own calculation at 40 kg -- entering a heavier Weight still returns the 40 kg result (Daily Volume and Hourly Rate stop climbing further) and sets Exceeds Pediatric Formula Range to true, flagging that standard adult maintenance fluid dosing should be used instead of this pediatric formula. Weight is the only input, and it drives every output below that ceiling: there is no separate age or clinical-status field, because the Holliday-Segar formula itself is defined purely by weight. A safety floor holds the effective weight at a minimum of 0.5 kg so the formula does not break down for an implausible or blank entry. Enter the patient's actual measured body weight for most patients -- but in significant pediatric obesity, actual body weight can substantially overestimate true fluid needs (fluid requirements track metabolically active tissue more closely than total mass, and excess fat mass is not metabolically equivalent to lean tissue), so some clinicians use an adjusted or ideal body weight instead in that scenario; which weight convention applies is a clinical judgment this calculator does not make. This estimates ROUTINE MAINTENANCE fluid needs only -- it does not account for pre-existing dehydration or deficit, ongoing abnormal losses (fever, vomiting, diarrhea, drain output), or a clinician's decision to restrict or liberalize fluids for a specific condition; those require a clinical adjustment on top of this baseline.