Calculators · Paediatrics & Neonatology · Formula
APLS age-based weight estimation
Also called APLS weight formula, paediatric weight by age, emergency weight estimate child
Estimates a child's weight from age when weighing is impossible (APLS: 0–12 months, 1–5 years, 6–12 years).
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Formula and scoring
0–12 months: weight (kg) = (0.5 × age in months) + 4. 1–5 years: (2 × age in years) + 8. 6–12 years: (3 × age in years) + 7. Age in completed months/years.
Exam and ward pearls
- Three age bands: infants use months, 1–5 years double and add 8, 6–12 years triple and add 7.
- Alternatives include length-based tapes (Broselow) and habitus-adjusted methods (PAWPER, Mercy).
When not to rely on it
- Derived in Western populations; accuracy varies in other populations, and wasted or obese children will be mis-estimated.
- Not for adolescents above 12 years.
Source
- O'Leary F, John-Denny B, McGarvey K, Hann A, Pegiazoglou I, Peat J. Estimating the weight of ethnically diverse children attending an Australian emergency department: a prospective, blinded, comparison of age-based and length-based tools including Mercy, PAWPER and Broselow. Arch Dis Child. 2017;102:46-52 (Methods: APLS formulas 0–12 months, 1–5 years, 6–12 years). doi:10.1136/archdischild-2016-310917 · PMID 27799153
Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.