Babies, toddlers & children
Baby & Child Age Calculator
Find your baby’s or child’s exact age in weeks, months and years from their date of birth, plus their developmental stage and corrected age if they were born early.
By Sandeep · Updated November 2026
How old is my child?
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Child Age Calculators & Guides
How to Use the Baby & Child Age Calculator
- Enter your child’s date of birth.
- Leave “Age on” as today’s date, or change it to a past or future date, such as a check-up or school start.
- If your baby was born before 37 weeks, enter how many weeks early to see corrected age as well.
- Press Calculate Age to see the age in weeks, months and years, plus your child’s stage.
This age calculator of baby and child ages uses real calendar months, so leap years and months of different lengths are counted exactly. It works for any child, from a newborn to a teenager.
Baby & Child Age Calculator Examples
Here is what the child age calculator shows for three children on 31 October 2026:
| Born | Main result | Stage |
|---|---|---|
| 20 August 2026 | 10 weeks, 2 days | Infant (baby) |
| 15 June 2025 | 16 months, 16 days | Toddler |
| 10 March 2021 | 5 years, 7 months, 21 days | School-age child |
The headline result switches format with age, just as parents and doctors do: weeks for young babies, months for toddlers, and years, months and days for older children. Every other unit is shown underneath, so this baby age calculator also works as an age calculator of child ages for school forms, daycare applications and doctor visits.
Weeks, Months or Years: Which Should You Use?
| Child’s age | Usually described in | Example |
|---|---|---|
| Birth to about 3 months | Weeks | “She’s 10 weeks old” |
| 3 months to about 2 years | Months | “He’s 18 months” |
| 2 to 3 years | Years and months | “2 and a half” |
| Over 3 years | Years (exact Y;M;D for tests) | “5 years old” |
Parents often switch between units, which is why a baby age calculator from weeks to months is so handy. A month is about 4.35 weeks, so 13 weeks is roughly 3 months and 26 weeks is about 6 months. The calculator does the exact conversion for you.
Stages of Child Development by Age
| Stage | Typical age |
|---|---|
| Newborn | Birth to 1 month |
| Infant (baby) | 1 to 12 months |
| Toddler | 1 to 3 years |
| Preschooler | 3 to 5 years |
| School-age child | 5 to 12 years |
| Teenager | 13 to 18 years |
Exact ages for each stage vary slightly between sources, but these are the common groupings used by pediatricians and parenting guides. Developmental milestones are usually tracked by month in the first two years. To compare skills with age, see the developmental age calculator.
Why Use a Dedicated Age Calculator of Child Ages?
A general age calculator usually gives the answer in years only, which is not much help for a 7-month-old. A child age calculator built for families shows the units you actually need at each stage, flags corrected age for premature babies, and tells you the date of the next month-birthday, which many parents like to mark with photos in the first year. It also saves mental math at busy moments, such as filling in a form at the doctor’s office or checking whether a toy is suitable for your child’s age.
Corrected Age for Babies Born Early
If your baby arrived before 37 weeks, doctors usually judge growth and milestones by corrected age until about age 2. Enter the weeks born early above, or use our dedicated corrected age calculator for more detail.
When Exact Child Age Matters
- Well-child visits and vaccines, which follow age-based schedules.
- Growth charts, which plot weight and height by age in months.
- Daycare and school entry, which use cut-off dates. Try the school age calculator.
- Developmental screenings and tests, which need the age to the day. See our chronological age calculator.
- Clothing and toy sizes, often labelled by age in months.
Baby & Child Age Calculator FAQs
What is the age calculator of a child?
It is a tool that finds a child’s exact age from their date of birth. This one shows the age in weeks, months and years, the developmental stage and corrected age for babies born early.
How do I calculate my baby’s age in weeks?
Count the days since birth and divide by 7. A baby born 75 days ago is 10 weeks and 5 days old. The calculator above does this instantly.
How do I convert my baby’s age from weeks to months?
Divide the weeks by about 4.35. For example, 13 weeks is about 3 months. For an exact answer by calendar months, use the calculator.
When do you stop saying a baby’s age in months?
Most parents switch to years around age 2, and to whole years after about age 3.
What age is a toddler?
A toddler is usually a child aged 1 to 3 years.
Is a 3 year old a toddler or preschooler?
A 3 year old is often described as both: at the end of the toddler stage and the start of the preschool years.