Pediatric Age-Based Weight Estimate

It reproduces two historical population-derived age-only estimates from completed age: the 2011 revised APLS 1–5-year branch and Luscombe–Owens for completed ages 1–13. It does not measure or validate an individual child’s weight.

The 2011 revised APLS 1–5-year branch is weight (kg) = 2 × completed age + 8. Luscombe–Owens is weight (kg) = 3 × completed age + 7 and is shown here for completed ages 1–13.

Completed age means the whole number of years reached at the last birthday. Do not enter months or a decimal age, and do not round a fractional age into this calculator.

Both historical sources apply in that page range: revised APLS uses 2 × age + 8, while Luscombe–Owens uses 3 × age + 7. They may produce different population estimates, but the difference does not identify which value is the child’s actual weight.

The revised APLS 6–12 expression is numerically the same 3 × age + 7 expression as Luscombe–Owens, so the page does not duplicate the same number under two labels. Ages 6–13 therefore show the independently sourced Luscombe–Owens estimate once.

Use a current measured weight when available, followed by a reliable recent or caregiver-reported weight or a validated length-based method that accounts for body habitus. A historical age-only formula is a final fallback; local equipment, protocols, and clinical judgment still apply.

Systematic reviews find low overall accuracy and potentially substantial individual error. Age alone does not capture height, body habitus, illness, population, country, or era differences. The formula cannot validate a child’s true weight.

No. It is a historical age-only estimate, not measured actual weight, normal or ideal weight, lean or adjusted dosing weight, or a growth-chart result. Growth assessment requires measured age- and sex-specific weight and height or length data.

Not automatically. This page does not generate a medication dose, fluid volume, equipment size, defibrillation energy, or resuscitation setting. A drug or protocol may require a different dosing-weight concept and independent verification.

Age-only formulas may underestimate actual weight where obesity is more common and overestimate it where malnutrition is more common. Chronic illness, edema, fluid shifts, amputation, and unusual body habitus can further separate an estimate from measured weight.

No. This page accepts completed ages 1–13 only. It does not provide an infant-month or neonatal formula and does not extend the equations beyond completed age 13.

Document the estimation method, the completed age entered, the estimate, the time, why measured or better weight information was unavailable, and any independent clinical verification. Record the measured weight later when it becomes available.