From due date to birthday
Your due date is the best single estimate of your baby’s birthday — but the real birthday could be any day in a window of about five weeks. This calculator shows both: the estimated birthday (40 weeks) and the birth window from 37 to 42 weeks, along with the month or months it covers.
For fun, it also shows the zodiac sign, birthstone and season of the due date — the kind of details many parents enjoy thinking about, as long as they are taken lightly.
When babies are actually born
Most babies are born at term, between 37 and 42 weeks, and the largest share around 39–40 weeks. First babies are slightly more likely to arrive after their due date than babies of second or later pregnancies. Twins tend to arrive earlier — see the Twin Due Date Calculator.
Birthstones by month
| Month | Birthstone | Month | Birthstone |
|---|---|---|---|
| January | Garnet | July | Ruby |
| February | Amethyst | August | Peridot |
| March | Aquamarine | September | Sapphire |
| April | Diamond | October | Opal |
| May | Emerald | November | Topaz |
| June | Pearl | December | Turquoise |
Can you choose a birth date?
Birth timing is not something to plan around a sign or a date. Planned inductions and caesarean births are scheduled for medical reasons, and current guidance is to avoid planned birth before 39 weeks unless there is a medical need. Your care team will advise what is safest for you and your baby.