All About Newborn, Infant, Baby, and Toddler Age Ranges

Newborn, baby, infant, and toddler are all words that may be used to describe your little one as they make their way from birth to that first day of preschool. But when is a baby no longer a newborn and when is a baby a toddler? Although there are no set definitions and no standard age ranges for newborns, babies, infants, and toddlers, we’ve gathered some information to help you understand the different ways these terms are used and the developments you may notice during these stages.

Newborn, Baby, and Infant Age

You may have heard your new bundle of joy being referred to as a newborn, infant, or baby. Many parents wonder “how long is a baby a newborn?” Although some of these terms can be used interchangeably, as there’s no set age range, some experts use newborns for those under 28 days of age, while other experts apply the name newborns to little ones up to 2 months old or even 3 months of age.

So, a newborn age range can extend from birth to around 1 month, 2 months, or 3 months of age. However, your little one can also be referred to as a baby or infant during this time, up until they’re about 1 year old.

Child Developmental Stages: Newborn, Baby, Infant Age

Every child is unique and develops at their own rate, but in your little one’s first year you can expect some big leaps in their growth and development. Here are some exciting developments that you may notice by the time your baby is 1 year of age.

  • Their first smile

  • Your newborn’s vision becoming more focused, and being able to see colors and objects in the distance

  • Reaching out for items

  • Starting to understand certain words, such as “no,” and recognizing the names of people

  • Waving “bye-bye!”

  • Babbling or saying “mama” or “dada”

  • Developing bonds and trust with loved ones and caretakers

  • Playing games, such as peekaboo or patty-cake

  • Crawling or pulling themselves up to stand

  • Walking along while holding onto furniture

  • Possibly taking their first steps

  • Developing fine motor skills, such as the pincer grasp, picking up small objects using their thumb and pointer finger.

As your little one grows and transitions from a teeny tiny newborn into a more active baby, it’s natural to wonder if their development is on track. Every baby is unique and meets milestones at different rates, so don't hesitate to contact your baby's healthcare provider if you have any questions or concerns about their development.

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Toddler Age Range

It may feel like only yesterday that you were holding your tiny newborn in your arms, and now they’re an active baby who never stops moving! But when and at what age is a baby/infant considered a toddler? Most experts suggest toddlerhood starts at 1 year of age. This is the time when many babies are ready to "toddle"to take those first shaky steps. The toddler age range runs from around 1 year (12 months) to around 3 years of age.

Child Developmental Stages: Toddler Age

In the blink of an eye, your newborn has become a toddler, and with that comes increasing independence and curiosity about the world around them. Get ready for some of the exciting and interesting developments that you may see during your child’s toddler years.

  • Starting to walk and learning to walk alone and walk well

  • Beginning to run

  • Pulling their toys along behind them

  • Kicking a ball

  • Climbing

  • Feeding themselves

  • Imitating others’ behavior

  • Developing an awareness of themselves and understanding “mine” and “his/hers”

  • Playing enthusiastically alongside other children

  • Engaging in pretend play and make-believe

  • Sorting by shape and color

  • Following two- or three-step directions

  • Saying four- and five-word sentences.

Every child develops and meets these milestones on their own timeline during their toddler years, so be prepared for your child to take more or less time than other children of the same age. If you have any concerns about your toddler’s developmental progress, such as their walking or language skills, contact their healthcare provider.

Preschool Age Range

Now that you have a rough idea of newborn, infant, baby, and toddler age ranges, what comes after a toddler? Once your toddler is around 3 years old, they are often considered a preschooler. The preschool age range may extend from 3 years up until they are around 5 years old. How time flies!

The Bottom Line

Although your little one may always be a baby in your heart, there are some common terms that will be applied to them as they grow and develop. The term newborn is often used for babies under 28 days or even up to 2 or 3 months of age, according to experts. After this period (and even during the newborn stage), your little one may be referred to as a baby or an infant up until they’re around 1 year of age.

But when does your teeny tiny baby become a toddler? Experts commonly use the word toddler when babies turn 1 year of age. The toddler age range usually runs from 1 year to 3 years of age, and before you know it, your little one will be a preschooler! Each of these stages brings its own exciting developmental milestones and learning curves for your child. So, enjoy the journey!

How We Wrote This Article The information in this article is based on the expert advice found in trusted medical and government sources, such as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.