Resuscitation and airway
Weight estimation by age
APLS formulas for an estimated weight when the child can't be weighed.
For education. Check against your unit's guidance and a second clinician before use.
Completed years, or months for babies under 1 year. For 0 to 12 years.
Fill in the boxes above to see the result.
Before you use this
- Use a measured weight whenever you can, and replace the estimate as soon as a weight is available.
- Formulas are less accurate for children who are small or large for their age.
- Around the world: length-based tapes (such as the Broselow tape) are widely used in North America, and formulas built on high-income populations can overestimate weight in low- and middle-income settings.
How this is calculated
- 0 to 12 months: weight (kg) = (0.5 × age in months) + 4
- 1 to 5 years: weight (kg) = (2 × age in years) + 8
- 6 to 12 years: weight (kg) = (3 × age in years) + 7
Sources
- Advanced Life Support Group. Advanced Paediatric Life Support (APLS), 6th edition. Wiley-Blackwell, 2016.
- Luscombe M, Owens B. Weight estimation in resuscitation: is the current formula still valid? Arch Dis Child 2007;92:412–5.
Checked by PICUlearn, 21 Sept 2026.