🧒 Pediatric Weight Estimation (APLS)
This tool estimates a child's weight from age using the APLS/Luscombe formulas when weighing is not possible.
The estimate is for emergencies only — when weighing is possible the measured weight always takes precedence. (original synthesis · not guideline verbatim)
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When to use
Use in emergencies to derive a working weight for drug dosing, equipment sizing, and defibrillation energy.
How it works
Months: 0.5 × months + 4. Years 1–5: 2 × years + 8. Years 6–12: 3 × years + 7.
Key points
- The estimate is for emergencies only — when weighing is possible the measured weight always takes precedence. (original synthesis · not guideline verbatim)
- Deviation is large in obese or developmentally atypical children.
- Different formulas apply to infants versus older children, so the correct age band must be selected.
References
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Age unit | Months (0–12 months) |
|---|---|
| Age | 3 |
→Estimated weight5.5kg
- Formula：0.5 × months + 4
| Age unit | Years (1–12 years) |
|---|---|
| Age | 3 |
→Estimated weight14kg
- Formula：2 × years + 8
Frequently asked questions
- What is Pediatric Weight Estimation (APLS)?
- This tool estimates a child's weight from age using the APLS/Luscombe formulas when weighing is not possible.
- How is Pediatric Weight Estimation (APLS) calculated? What is the core formula?
- Months: 0.5 × months + 4. Years 1–5: 2 × years + 8. Years 6–12: 3 × years + 7.
- When is Pediatric Weight Estimation (APLS) used?
- Use in emergencies to derive a working weight for drug dosing, equipment sizing, and defibrillation energy.
- What are the key clinical points for Pediatric Weight Estimation (APLS)?
- The estimate is for emergencies only — when weighing is possible the measured weight always takes precedence. (original synthesis · not guideline verbatim) Deviation is large in obese or developmentally atypical children. Different formulas apply to infants versus older children, so the correct age band must be selected.
- What are the limits and cautions when using Pediatric Weight Estimation (APLS)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Pediatric Weight Estimation (APLS) calculated in practice? Can you show a worked example?
- Inputs: Age unit Months (0–12 months), Age 3 → Result: Estimated weight 5.5 kg（Formula: 0.5 × months + 4） Inputs: Age unit Years (1–12 years), Age 3 → Result: Estimated weight 14 kg（Formula: 2 × years + 8）