Baby Milestone Tracker
Look up expected developmental milestones by your baby's age in months.
Covers motor skills, language, social development, and when to consult a pediatrician.
Baby developmental milestone tracking compares a child’s current age against established age ranges for developmental achievements across motor, language, social, and cognitive domains. These ranges are based on large population studies by the CDC and WHO.
Age calculation formula: Corrected Age = Chronological Age − Weeks Premature (for premature babies) Chronological Age = Current Date − Birth Date (in weeks or months)
Use corrected age (also called adjusted age) for all milestone comparisons until the child is 24 months old, if they were born more than 3 weeks early.
What each variable means:
- Chronological age — the baby’s actual age from birth date.
- Corrected age — for premature infants, development is measured from the expected due date, not the actual birth date. A baby born 8 weeks early at 6 months chronological age has a corrected age of approximately 4 months.
- Milestone range — each milestone has an age range (not a fixed date). The range represents the normal window across healthy children. Reaching a milestone at the later end of the range is not a concern unless multiple domains are delayed simultaneously.
Key developmental milestone ranges (CDC 2022):
| Milestone | Age Range |
|---|---|
| Social smile | 1–2 months |
| Holds head steady | 2–4 months |
| Rolls from tummy to back | 3–5 months |
| Sits without support | 5–9 months |
| Crawls | 6–10 months |
| Pulls to stand | 8–12 months |
| First words (1–3 words) | 10–14 months |
| Walks independently | 9–18 months |
| 10+ words vocabulary | 12–18 months |
| Two-word phrases | 18–24 months |
| 50+ word vocabulary | 21–24 months |
Worked example: Baby born on January 1, 2025. Current date: July 15, 2025. Chronological age = 6 months, 14 days ≈ 6.5 months
Baby can sit briefly with support but not independently. Sitting without support range: 5–9 months → within normal range, no concern.
Baby has not yet rolled over. Rolling range: 3–5 months → at upper edge/slightly late — worth monitoring and mentioning to pediatrician at next visit. Single isolated delay is usually not significant.
Important: These ranges are screening guides only. Always consult your pediatrician with concerns. Early intervention for genuine delays is highly effective — early identification is a gift, not a judgment.