Baby Age Calculator: Weeks, Months & Days
Wondering exactly how old your little one is? Our online Baby Age Calculator uses their date of birth to give you a precise age in years, months, weeks, and days, so you can track every precious milestone from the moment they are born.
Baby's Age Calculator
Enter your baby's birthday to see their age in weeks, months, and days.
Learn More About Pregnancy & Baby Milestones
How to Use the Baby Age Calculator
- Enter Your Baby's Date of Birth: Use the input fields (DD, MM, YYYY) to enter their exact birthday.
- Click "Calculate Baby's Age": Press the button to get an instant result.
- View the Results: The tool will show your baby's age in three useful formats:
- Years, months, and days for a standard view.
- Total weeks and days, which is common for newborns.
- Total months and days.
Why Use a Baby Age Calculator?
In the first couple of years, a baby's development happens at lightning speed. Using an online age calculator to track their age from their date of birth is important for several reasons:
- Doctor's Appointments: Pediatricians track growth and schedule vaccinations based on the baby's age in weeks and months.
- Developmental Milestones: Knowing your baby's precise age helps you understand if they are on track for milestones like rolling over, sitting up, and talking.
- Feeding Schedules: A baby's nutritional needs change rapidly. Age in weeks and months often dictates when to introduce solid foods.
- Clarity: It answers the common confusion between weeks and months. For example, a baby is 3 months old, not at 12 weeks, but after 3 full calendar months have passed.
Baby Age Chart: Weeks to Months and Days
This baby age chart provides a quick conversion from weeks to months to help you visualize your baby's growth.
| Age in Weeks | Equivalent Age in Days | Equivalent Age in Months |
|---|---|---|
| 4 weeks | 28 days | Approx. 1 month |
| 8 weeks | 56 days | Approx. 2 months |
| 12 weeks | 84 days | Approx. 3 months |
| 16 weeks | 112 days | Approx. 4 months |
| 20 weeks | 140 days | Approx. 5 months |
| 24 weeks | 168 days | Approx. 6 months |
| 36 weeks | 252 days | Approx. 9 months |
| 52 weeks | 364 days | 1 year |
Corrected Age for Premature Babies
If your baby was born prematurely (before 37 weeks of pregnancy), your pediatrician will likely use a "corrected age" to track their development. Corrected age is the baby's chronological age minus the number of weeks they were born early.
For example, if your baby is 16 weeks old but was born 4 weeks early, their corrected age is 12 weeks. This adjusted age is used to evaluate developmental milestones because premature babies need time to catch up.
This calculator determines the **chronological age** (the time since birth). Always consult your healthcare provider about your premature baby's development based on their corrected age.