Baby Age Calculator
Enter your baby's date of birth to find their exact age in weeks, months, and days — plus age-appropriate developmental milestones.
Baby Age by Weeks (0-12)
The first 12 weeks of life involve rapid changes. Here is a general guide to what you can expect week by week during the newborn and early infant period:
| Week | What to Expect |
|---|---|
| Week 1 | Adjusting to life outside the womb. Sleeping 16-17 hours a day. Feeding every 2-3 hours. |
| Week 2 | Umbilical cord stump may fall off. Beginning to focus on faces at close range (8-12 inches). |
| Week 3 | May start lifting head briefly during tummy time. Becoming more alert during awake periods. |
| Week 4 | One month old. Can track objects with eyes. May respond to loud sounds by startling. |
| Week 5 | First social smile may appear. Arm and leg movements become smoother and less jerky. |
| Week 6 | Smiling more frequently. Starting to coo and make vowel sounds. Better head control. |
| Week 7 | Discovering hands. May start bringing hands together and watching them move. |
| Week 8 | Two months old. Making more varied sounds. Beginning to follow moving objects with eyes. |
| Week 9 | Improved neck strength. May hold head at 45 degrees during tummy time. |
| Week 10 | Grasping objects placed in hand. Social smiling is well established. |
| Week 11 | May begin to laugh or squeal. Increasingly interested in surroundings and faces. |
| Week 12 | Three months old. Holds head up steadily. Coos, babbles, and responds to voices. |
Baby Age by Months (1-24)
As your baby grows through the first two years, developmental milestones provide a helpful framework for tracking progress. Remember that every child develops at their own pace — these are typical ranges, not strict deadlines.
| Month | Key Milestones |
|---|---|
| 1 month | Lifts head briefly, focuses on faces, responds to sounds, strong grasp reflex |
| 2 months | Social smiling, tracks objects, coos, holds head up during tummy time |
| 3 months | Laughs, reaches for objects, holds head steady, opens and shuts hands |
| 4 months | Rolls front to back, bears weight on legs when held, babbles consonant sounds |
| 5 months | Reaches for and grasps toys, rolls in both directions, recognizes familiar people |
| 6 months | Sits with support, starts solid foods, responds to own name, passes objects between hands |
| 7 months | Sits without support, explores objects by banging and shaking, stranger anxiety may begin |
| 8 months | Crawling or scooting, pulls to stand, uses pincer grasp, says "mama" or "dada" (non-specific) |
| 9 months | Stands holding furniture, points at objects, understands "no", plays peek-a-boo |
| 10 months | Cruises along furniture, waves bye-bye, improved pincer grasp, explores cause and effect |
| 11 months | May stand alone briefly, follows simple instructions, says 1-2 words with meaning |
| 12 months | First birthday. May take first steps, says 1-3 words, drinks from cup, imitates actions |
| 15 months | Walking well, says 3-5 words, stacks 2 blocks, uses spoon (messily), points to show interest |
| 18 months | Runs stiffly, says 10-20 words, scribbles, follows simple directions, begins pretend play |
| 21 months | Kicks a ball, uses 2-word phrases, sorts shapes, names body parts, helps with undressing |
| 24 months | Second birthday. Runs easily, 50+ words, 2-word sentences, jumps with both feet, parallel play |
When to Use Adjusted Age
If your baby was born before 37 weeks of gestation, pediatricians recommend tracking developmental milestones using adjusted age (also called corrected age) rather than chronological age. Adjusted age accounts for the weeks of prematurity by subtracting them from the baby's chronological age.
For example, a baby born at 34 weeks (6 weeks early) who is chronologically 4 months old has an adjusted age of about 2.5 months. Milestones should be compared against the adjusted age, not the chronological age, until the child is 2 to 3 years old. This gives preemies a fairer developmental assessment and reduces unnecessary parental worry.
Most premature babies catch up to their full-term peers by age 2-3 in most areas of development. If you have concerns about your preemie's progress, speak with your pediatrician or a developmental specialist.
Need adjusted age for a preemie? →
Related Tools
Use our full chronological age calculator for an exact age calculation in years, months, and days. For premature babies, our adjusted age calculator provides corrected age based on gestational age at birth.
Frequently Asked Questions
To calculate your baby's age in weeks, count the total number of days from their date of birth to today, then divide by 7. For example, if your baby was born 45 days ago, they are 6 weeks and 3 days old. Our baby age calculator does this automatically — just enter the date of birth and get the result instantly in weeks, months, and days.
Babies reach milestones at different rates, but general guidelines include: social smiling at 6-8 weeks, holding head up at 3-4 months, rolling over at 4-6 months, sitting without support at 6-7 months, crawling at 7-10 months, first words at 10-14 months, and walking at 9-16 months. Remember that these are ranges, not deadlines — every baby develops at their own pace. If you have concerns, consult your pediatrician.
Yes. If your baby was born before 37 weeks of gestation, pediatricians recommend using adjusted (corrected) age for tracking developmental milestones until age 2-3. Adjusted age accounts for the weeks of prematurity. For example, a baby born at 32 weeks (8 weeks early) who is chronologically 6 months old has an adjusted age of about 4 months. Use our adjusted age calculator to calculate corrected age for your preemie.