How old is she exactly? Down to the day.
Add her birth date and this baby age calculator gives her age in days, in weeks and days, and in months and days. Born early? Add the due date too and you’ll get her corrected age. No account, and nothing you type gets sent anywhere.
Work out an age
112 days old: 16 weeks, or 3 months, 22 days.
| In days | 112 days |
|---|---|
| In weeks | 16 weeks |
| In months | 3 months, 22 days |
How many weeks old is my baby?
Count the days since she was born and divide by seven. A baby born on January 15 is 21 days old on February 5. That’s exactly 3 weeks. On February 7 she’s 3 weeks and 2 days.
For the first couple of months everyone counts in weeks: appointments, feeding guidance, the first vaccinations. Then months take over, and the two don’t line up. She’ll be 4 weeks old a few days before she’s one month old, every month of the year except February.
This calculator counts calendar months. Born on January 15, she’s one month old on February 15 and two months old on March 15, even though the first month has 31 days and the second has 28. That’s how a pediatrician counts, and how the growth charts are labeled.
What is corrected age, and how do you work it out?
It’s the age a baby born early would be if she’d arrived on her due date, and some doctors call it adjusted age. Take the weeks she came early off her age. Born eight weeks early and twelve weeks old today? Her corrected age is four weeks.
Growth charts and most milestones count from the due date. A baby born two months early has had two fewer months to grow than her birthday suggests, so going by her age from birth, she’d be compared with babies who’ve had two more months.
Tired of counting weeks? Bundle of Joy knows her birthday, so the growth chart always shows how old she is, and every measurement lands at the right age.
The other free tools
- WHO growth chart calculator. Plot weight, height or head circumference and get the percentile.
- Baby weight converter. Kilograms to pounds and ounces, centimeters to inches.
- Diaper size calculator. Which sizes fit a given weight.
- Formula amount calculator. What the AAP and NHS guidelines say for a weight.
Let the app do the counting.
Feeds, diapers and growth, shared with your partner.
