Most healthy, full-term babies double their birth weight sometime around the middle of their first year. This is a general guideline, not an exact deadline.

Typical timing

Most sources describe that babies usually double their birth weight by about 4 months of age, with many falling in a broader range of about 4 to 6 months. Some pediatric references note that this rapid weight gain tends to slow after 6 months, but the “double by around 4 months” pattern is still a common benchmark.

Normal variation

There is wide normal variation, and some perfectly healthy babies reach double their birth weight a bit earlier or later than this window. Doctors pay more attention to steady growth along a curve, good feeding, wet diapers, and meeting developmental milestones than to whether the exact “double” point happens on time.

When to call the doctor

Contact the baby’s pediatrician if:

• Weight has not doubled by around 6 months and growth has been slow over several checkups.

• There are other concerns like poor feeding, very few wet diapers, lethargy, or illness, as these can affect weight gain and may need evaluation.