Which formula should I use?

APLS is widely taught for ages 1–10. Luscombe & Owens and Best Guess are alternatives — compare and use local guidance.

What about Broselow tape?

Broselow is length-based and preferred in many EDs when available; this tool is age-based when length is unknown.

Pediatric Weight Estimation

Medical context

Estimate pediatric weight from age using APLS, Luscombe & Owens, and Best Guess formulas — plus infant and neonate modes.

Pediatric teams must confirm age-appropriate references and weight-based dosing with local protocols.

This page explains the Peds Weight formula, how to interpret the output, known limitations, and peer-reviewed references so you can verify results against primary sources and local protocols.

It is grouped under Pediatrics because neonatal and pediatric medical calculators.

How to use this calculator

Enter the values requested by the Peds Weight calculator using the units shown beside each field.
Review the calculated result and read the interpretation section before acting on the output.
Check limitations and references if the result will change management, dosing, or disposition.
Use the related calculators section when you need supporting values (for example electrolytes, weight, or complementary risk scores).

Calculator

Age input

Age (years)APLS validated roughly 1–10 years

Result

18 kg

APLS estimate · age 5 y

APLS (age+4)×2: 18 kg
Luscombe & Owens (3×age+7): 22 kg
Best Guess 5–14 y (4×age): 20 kg

Educational use only. Confirm results with clinical judgment, primary sources, and local protocols. Not a substitute for professional medical advice. Full disclaimer.

Formula

APLS child: (age+4)×2. Infant: age(months)/2 + 4. Luscombe: 3×age + 7. Best Guess: 2×age+8 (1–4y) or 4×age (5–14y).

Interpretation

Use as an emergency estimate when a scale is unavailable. Prefer measured weight for drug dosing whenever possible.

Limitations

Population growth changes over time; obese/underweight children diverge. Not a substitute for weighing.

Frequently asked questions

Which formula should I use?: APLS is widely taught for ages 1–10. Luscombe & Owens and Best Guess are alternatives — compare and use local guidance.
What about Broselow tape?: Broselow is length-based and preferred in many EDs when available; this tool is age-based when length is unknown.
Is the Peds Weight result enough to make a treatment decision?: No. Calculators support medical decision-making but do not replace examination, shared decision-making, institutional protocols, or consultant input when stakes are high.

References

APLS / EPALS weight estimation teaching
Luscombe M, Owens B. Arch Dis Child. Weight estimation.
Tinning K, Acworth J. Best Guess. Emerg Med Australas.