Pediatric Weight Estimation — Free Online Calculator
Input
Note: These are estimates only. Actual measured weight should always be used when available.
APLS Estimated Weight
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About This Calculator
Pediatric weight estimation formulas provide an approximate body weight when a child's actual weight cannot be measured (e.g., emergency situations). The APLS formula is age-dependent with three ranges, while the Luscombe formula uses a single equation for ages 1–12. These are estimates only — actual measured weight should always be used when available. The Broselow tape is another common method for weight-based dosing in emergencies.
Formula
Interpretation
| Age | APLS Estimate | Typical Range |
|---|---|---|
| Newborn | 4 kg | 2.5–4.5 kg |
| 6 months | 7 kg | 5.5–8.5 kg |
| 1 year | 10 kg | 8–12 kg |
| 5 years | 18 kg | 15–22 kg |
| 10 years | 37 kg | 28–45 kg |
References
- Luscombe M, Owens B. Weight estimation in resuscitation: is the current formula still valid? Arch Dis Child. 2007;92(5):412-415.
- Advanced Paediatric Life Support (APLS): The Practical Approach. 6th ed. BMJ Books; 2016.
Frequently Asked Questions
How accurate are weight estimation formulas?
Weight estimation formulas have limited accuracy, particularly in malnourished or obese children. Studies show they are within 20% of actual weight about 60–70% of the time. The Broselow tape (length-based) may be more accurate in children under 10. Always measure actual weight when possible.
Which formula should I use?
The APLS formula is most widely taught in pediatric resuscitation courses. The Luscombe formula may slightly overestimate compared to APLS for older children. In practice, the difference is small. Use whichever formula your institution recommends.
Do these formulas work for adolescents?
These formulas are designed for children up to age 12. For adolescents, weight varies greatly and is not reliably estimated by age alone. The Broselow tape only works up to ~36 kg. For adolescents, ask the patient, caregiver, or use recent medical records.
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⚠ Medical Disclaimer
This tool is for educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for clinical decisions.