👶 Baby Age Calculator
Enter your baby's date of birth to get their exact age in weeks and days, plus the equivalent in months — along with a general developmental stage label.
Weeks, months and days old, with a general developmental-stage label.
How the Baby Age Calculator works
The calculator counts total days since birth and converts that into weeks, months, and a general stage category (newborn, infant, toddler, or preschooler) based on standard age brackets.
Step-by-step calculation
- 1Enter the baby's birth date.
- 2Days since birth are counted.
- 3See weeks, months and the life stage.
Worked example
A baby born June 1, 2026 is 166 days old on November 14, 2026 — 23 weeks 5 days, or 5 months 13 days.
Baby Age Calculator examples
| Baby's date of birth | Age |
|---|---|
| Dec 1, 2025 | 4 weeks, 3 days old (1 months, 0 days) |
| Oct 15, 2025 | 11 weeks, 1 days old (2 months, 17 days) |
| Jul 1, 2025 | 26 weeks, 2 days old (6 months, 0 days) |
| Jan 1, 2025 | 52 weeks, 1 days old (1 year, 0 months, 0 days) |
| Jun 1, 2024 | 82 weeks, 5 days old (1 year, 7 months, 0 days) |
Calculated as of January 1, 2026. Other inputs kept at the calculator's default values. Results calculated by this calculator.
Why use a Baby Age Calculator?
Track milestones, feeding and checkups by your baby's exact age.
Important factors that can affect your results
- Premature babies may use adjusted age.
- Months counted on the calendar versus 4-week blocks.
- Doctors often speak in weeks until about 3 months.
Frequently asked questions
Why is baby age often measured in weeks instead of months?
In the first year especially, weeks give a more precise picture of development than months, since a "month" isn't a fixed number of days.
Is the developmental stage label a medical assessment?
No — it's a general age-range label only, not a developmental or medical assessment. Talk to a pediatrician for anything development-related.
Related calculators
Last reviewed November 2026 · How we build and check our tools · Report a problem