Child Carrier Guide / Calculation
How the outgrow age is calculated
The outgrow estimate places a child on the WHO weight-for-age curve for the child's age and weight. It then follows the same curve forward to the month where it meets the carrier's weight limit.
Steps
- WHO publishes three values for each age, called L, M and S. The child's position on the curve is z = ((weight / M)L minus 1) / (L times S).
- For each later month, the weight on the same curve is M times (1 + L times S times z)1/L.
- The estimate is the first month at or above the carrier's child maximum of 18 kg. LittleLife carriers also stop at 36 months, their listed maximum age.
- The WHO standard for ages 0 to 5 ends at 60 months. Later results show "after 5 years".
Comparison with WHO's printed table
Medians calculated from the expanded tables for boys at 12, 24, 36, 48 and 60 months are 9.6, 12.1, 14.3, 16.3 and 18.3 kg. WHO's simplified field table lists 9.6, 12.2, 14.3, 16.3 and 18.3 kg. The 0.1 kg difference at 24 months is rounding.
Fit comparisons
The fit finder compares weight with the listed child minimum and maximum, and age with the listed minimum age. It compares height with Deuter's pack height ranges and foot length with Merrell's size chart. Nothing is estimated where a manufacturer lists no limit.
The outgrow age is a statistical projection, not a medical assessment. A pediatrician answers questions about a child's growth.