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Baby Age Calculator
Work out exactly how old your baby is, in months, weeks, days and even hours, plus the corrected (adjusted) age if your baby was born early. Handy for tracking milestones, vaccinations and feeding.
Your baby is
What is corrected (adjusted) age?
If your baby arrived early, their development is measured from their due date, not their birth date. That adjusted figure is the corrected age, and it gives a fairer picture of where your baby is at.
The maths is simple: corrected age = actual age minus the number of weeks your baby was born early (weeks early = 40 weeks minus how many weeks pregnant you were at birth). For example, a baby born at 32 weeks is 8 weeks early; at 4 months old (16 weeks), the corrected age is 16 minus 8 = 8 weeks, or about 2 months.
How long should I use corrected age?
Use corrected age to judge milestones and growth through roughly the first 2 years, by which point most premature babies have caught up. Some doctors continue correcting to around age 3 for very premature babies. Your paediatrician will guide you. For a full-term baby, corrected age and actual age are the same.
Weeks, months or years?
In the early days it is normal to count your baby's age in weeks (and that is how clinics often refer to it), then switch to months later in the first year and years after that. Note that 4 weeks is about 28 days, so it is not exactly the same as one calendar month, which is why a "months" figure and a "weeks" figure can look slightly different.
What to do at your baby's age
Once you know how old your baby is (corrected age for preemies), check what is typical for that stage:
- See the milestones for your baby's age with our milestone tracker.
- Check upcoming jabs on the Singapore vaccination schedule.
- Work out feeds with the milk feeding calculator.
If you have any worries about your premature baby's development, KKH and NUH run follow-up clinics for preterm infants, and your polyclinic or paediatrician can refer you.
Frequently asked questions
How do I calculate my baby's age in months?
Count the completed calendar months from the birth date to today, with any extra days shown on top. Enter the birth date above and we work it out for you, including weeks and total days.
Is 4 weeks the same as 1 month old?
Not exactly. Four weeks is 28 days, while a calendar month is about 30 to 31 days. So your baby in "weeks" will be slightly ahead of the same baby counted in "months".
What is corrected age and how do I work it out?
Corrected age is your baby's age counted from the due date instead of the birth date. It equals the actual age minus the weeks your baby was born early (40 weeks minus the weeks pregnant at birth).
How long do I use corrected age for?
Use it for milestones and growth until about 2 years old, when most premature babies have caught up. Very premature babies may be corrected for a little longer, on your doctor's advice.
What counts as premature?
A baby born before 37 completed weeks of pregnancy is premature (preterm). Full term is around 39 to 40 weeks.
I don't know my exact due date. What do I use?
If you know how many weeks pregnant you were at birth, choose "Born early (weeks)". Otherwise treat your baby as full term, the corrected and actual ages will simply be the same.
How should I count age for twins?
Use each baby's own birth date (they are usually the same) and the gestational weeks at birth. Twins are often born early, so corrected age is especially useful.
Can I check my baby's age on a past or future date?
Yes. Change the "work out age as of" date to any day to see how old your baby was or will be then, handy for appointments and birthdays.
