This baby age calculator is built around how parents actually think about a young child's age - in weeks and months, not years. Enter your baby's date of birth and instantly see their exact age broken down into years, months and days, plus how many weeks old they are, their current life stage, and the date of their next month milestone. It works just as well as an age calculator of child or toddler once they're past the baby stage.
The calculator uses the same calendar-accurate math as every other tool on this site: it takes the date of birth and today's date, then counts full years, full months and remaining days between them. For a baby, the months figure is usually far more meaningful than the years figure, so it's displayed prominently, alongside a total-weeks figure calculated directly from the total number of days since birth divided by seven. The calculator also works out the next "month-versary" - the next date the baby turns a whole number of months old - and shows how many days away that milestone is, which is what most baby-tracking apps and pediatrician appointment schedules are built around.
In the earliest weeks, many parents want to know exactly how many weeks old their baby is rather than months - useful for feeding schedules, newborn check-ups, and comparing early growth against weekly guidance from a health visitor or pediatrician. This tool covers that as a baby age calculator weeks to months tracker: the weeks figure is most useful in the first few months, while the months figure becomes more relevant as the baby grows into a toddler. The same calculation naturally works as a toddler age in months calculator too, right up through early childhood.
Alongside the exact age, the calculator shows a life stage label - newborn (under 1 month), infant (1 month to 1 year), toddler (1 to 3 years), or child (3 years and up) - so you get an at-a-glance sense of your child's developmental stage without having to do the month-counting yourself. This makes the tool useful as a simple child milestone age tracker alongside more detailed developmental checklists.
This calculator uses the actual date of birth to calculate age. Many parents of babies born early also track "adjusted age" - age counted from the original due date rather than the birth date - since development is often compared against the due date in the first year or two. If you want that adjusted figure, simply enter the due date instead of the actual birth date; the calculator will work identically either way.
Sign in to save your baby's (or several children's) dates of birth so you can pull them back up instantly next time, without retyping. Everything runs in your browser, there's no cost to use it, and it works instantly on any device - a simple, accurate baby age calculator for every stage from newborn to toddler.