Know exactly how old your infant is — down to the week. The infant stage (1–12 months) is a time of rapid growth. Track milestones, feeding, and sleep by your baby's precise age.
The Infant Age Calculator tracks your baby's exact age in weeks, months, and days. The infant stage spans from 1 month to 12 months (the first birthday). This is distinct from the newborn stage (0-3 months) which has its own unique characteristics and care requirements.
The newborn period is the first 3 months of life. Babies sleep most of the day, feed frequently, and begin developing early social smiles and visual tracking. This stage requires the most intensive care and frequent pediatric visits.
Babies become more interactive. They roll over, sit with support, reach for objects, and begin solid foods. Sleep patterns become more predictable. This is a period of rapid social and motor development.
Babies become mobile — crawling, pulling up, and possibly walking. They develop separation anxiety, say first words, and feed themselves finger foods. This stage prepares them for the transition to toddlerhood.
Why it matters: Tracking your infant's exact age helps you understand developmental milestones, feeding schedules, sleep patterns, and vaccine timing. Each week and month brings new changes — knowing what to expect helps you provide the best care for your growing baby.
Each month brings new developmental achievements: rolling over (4 months), sitting independently (6 months), crawling (8 months), standing (10 months), and first steps (12 months). Tracking age helps identify if your baby is meeting milestones at the expected time.
Infant vaccines are administered at specific ages: 2 months (DTaP, IPV, Hib, PCV, RV), 4 months (second doses), 6 months (third doses), and 12 months (MMR, varicella, hepatitis A). Knowing your infant's exact age ensures timely immunizations.
Feeding changes dramatically: exclusive breastfeeding/formula (0-6 months), introduction of solids (4-6 months), finger foods (8-10 months), and transition to table foods (12 months). Age-appropriate feeding prevents choking and supports optimal nutrition.
Newborns sleep 14-17 hours in short bursts. By 3-4 months, some babies begin sleeping longer stretches. By 6 months, many infants sleep through the night with 2-3 naps. By 12 months, most transition to 1-2 naps. Age-appropriate sleep expectations help parents establish healthy routines.
A newborn is 0-3 months old. An infant is 1-12 months old (the term "infant" comes from Latin "infans" meaning "unable to speak"). A baby is a broader term that can refer to both newborns and infants, typically up to 12 months. Some extend "baby" to include toddlers up to 18-24 months.
The American Academy of Pediatrics recommends starting solid foods around 6 months of age. Signs of readiness include: sitting with minimal support, good head control, loss of tongue thrust reflex, and showing interest in food. Always consult your pediatrician before starting solids.
Newborns (0-3 months): 14-17 hours/day. Infants (4-6 months): 12-16 hours/day including naps. Infants (7-12 months): 12-15 hours/day including 1-2 naps. Every baby is different — focus on your baby's cues rather than strict schedules.
Consult your pediatrician if your infant: doesn't respond to sounds by 3 months, doesn't track objects by 4 months, doesn't roll over by 6 months, doesn't sit without support by 9 months, doesn't babble by 6 months, or doesn't crawl by 12 months. Early intervention is crucial for developmental delays.
Average weight gain: 0-3 months: 150-200 grams per week (5-7 oz). 3-6 months: 100-150 grams per week (3.5-5 oz). 6-12 months: 70-90 grams per week (2.5-3 oz). Birth weight typically doubles by 4-5 months and triples by 12 months. These are averages — healthy babies vary widely.