Ideal body weight (pediatric)
- Category: General
- Version: v1.0.1
- Reviewed: Reviewed 6 Sep 2026
- Validation: Validation pending
Ideal body weight (kg) is estimated from height. The formulas are shown side by side because no consensus method exists. Traub–Kichen: IBW = 2.396 × e^(0.01863 × height in cm). It is sex-independent, validated 1–17 years, and is the primary paediatric height-based equation. Simplified Traub (Lexicomp): IBW = height² × 1.65 ÷ 1000, with height in centimetres. Moylan prints “inches”, an apparent transcription error yielding non-physiologic values. This method runs about 7% higher than Traub–Kichen. Devine (adult-derived, sex-based) is shown only at height ≥ 152.4 cm (60 in): 50.0 (male) or 45.5 (female) + 2.3 × (inches − 60). It over-estimates versus paediatric methods.
The methods disagree by ≥ 10 kg in some children and change prescribed tidal volumes in pediatric ARDS (Ward 2018), which is why each one is shown and none is silently chosen. IBW carries no bands: it feeds weight-based dosing, %-IBW nutritional classification, and lung-protective tidal-volume setting. The McLaren & Read categories attach to the %IBW ratio, not to IBW. Growth-chart reference methods (McLaren, Moore, ADA, BMI50) need percentile-table lookups and are documented, not implemented. Height-only equations are weakest below about 1–2 years.
References
- Traub SL, Kichen L. Estimating ideal body mass in children. Am J Hosp Pharm. 1983;40(1):107–110.Primary height-based pediatric IBW equation (A1); IBM = 50th-percentile weight for height; ages 1–17 y; sex-independent.PMID 6823980
- Kang K, Absher R, Farrington E, Ackley R, So T-Y. Evaluation of Different Methods Used to Calculate Ideal Body Weight in the Pediatric Population. J Pediatr Pharmacol Ther. 2019;24(5):421–430.Source for the simplified Traub (A2) and Devine (A3) formulas and for the seven-method comparison.PMID 31598106DOI 10.5863/1551-6776-24.5.421
- Ward SL, Quinn CM, Steurer MA, Liu KD, Flori HR, Matthay MA. Variability in Pediatric Ideal Body Weight Calculation: Implications for Lung-Protective Mechanical Ventilation Strategies in Pediatric ARDS. Pediatr Crit Care Med. 2018;19(12):e643–e652.PICU relevance: method choice shifts IBW by ≥10 kg in some children and changes prescribed tidal volume; the BMI method was usable in only 61% of a cohort.PMID 30277896DOI 10.1097/PCC.0000000000001740
- Moylan A, et al. Assessing the Agreement of 5 Ideal Body Weight Calculations for Selecting Medication Dosages for Children With Obesity. 2019.Cross-check of five methods; source of the simplified-Traub inches-vs-centimetres transcription-error flag (use centimetres).Source
- physiology R package — ideal_weight_Traub.Independent encoding of the Traub 1983 equation; cross-checks Worked example 1 (returns 15.44 kg at 100 cm); validated ages 1–17 y.Source
Reproduction rights
Freely reproducible.Formulas, coefficients, and numeric thresholds are facts / mathematical relationships, not copyrightable expression — Traub, simplified Traub, and Devine may be implemented freely (research §"IP status"). No verbatim proprietary scale text is reproduced.
Independent clinical validation: pending
Two independent clinical validators will be named here once review is complete.
- 2026-09-03v1.0.0Initial releaseInitial published text.
- 2026-09-06v1.0.1ClarificationAdded a one-line description for the catalogue card. No rule, threshold or reference changed.
Other general scores
- APLS age-based weight estimateAge-based weight estimate for when a child cannot be weighed
- Body surface areaBody surface area from height and weight, for mg/m² dosing and cardiac index
- Corrected QT intervalHeart-rate-corrected QT interval by Bazett and Fridericia
- FOUR scoreComa assessment that stays complete in an intubated patient
- Pediatric Glasgow Coma ScaleAge-adapted Glasgow Coma Scale for infants and children
Important. For use by qualified health professionals as an informational and educational aid. It supports clinical judgment and does not replace it. Verify every result independently before making a clinical decision. This is not a medical device.