What Is a Pediatric Weight Estimation (APLS) Calculator?
In a pediatric emergency, there often isn't time to place a child on a scale before the first dose of a resuscitation drug or fluid bolus is needed. The APLS (Advanced Paediatric Life Support) formula gives clinicians a fast, age-based estimate of body weight so treatment can begin immediately, without waiting for an actual measurement.
This calculator applies that same formula: enter a child's age in years and get an instant estimated weight in both kilograms and pounds.
How to Read Your Results
Estimated Weight
This is the calculated weight in kilograms, the unit most emergency drug dosing charts and infusion calculators use.
Weight in Pounds
The same estimate converted to pounds, useful for comparing against parent-reported weights in US units.
Age Range Check
The APLS formula is validated for children roughly 1 to 10 years old. Outside that range the calculator flags the estimate as less reliable — for infants under a year, a different age-in-months formula or a length-based (Broselow-style) method is more appropriate.
Real-World Example
A 6-year-old arrives in the emergency department with no known weight on record.
| Input | Value |
|---|---|
| Age | 6 years |
| Formula | (6 + 4) × 2 |
| Estimated weight | 20.0 kg (44.1 lb) |
That 20 kg estimate can be used to calculate an initial weight-based drug dose while an actual weight is obtained as soon as possible.
Tips for Using Age-Based Weight Estimates
- Replace the estimate with a real weight as soon as one becomes available — scales, parent report, or a length-based tape all take priority.
- Use with caution outside ages 1–10, where the formula's accuracy declines.
- Malnourished or obese children may differ significantly from the age-based estimate.
- Double-check high-risk drug doses calculated from an estimated weight against a second reference or colleague.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team