Baby and child

Estimate growth percentiles for weight, length, and head circumference, 0 to 5 years. See methodology for source details.

Look up sleep ranges by age, 0 to 18 years. See methodology for source details.

How growth percentiles are calculated and why a single number is not a verdict.

What sleep regressions are, what triggers them, and what actually helps.

How sleep architecture changes around 4 months and what helps.

Separation anxiety, motor milestones, and second-half-of-year sleep changes.

Review growth-percentile assumptions and source notes.

Review sleep-range assumptions and source notes.