Due Date Calculator
Predict your due date and week of pregnancy.
Tip: The due date is calculated as 280 days (40 weeks) from the first day of the last period.
Did this tool help?
About this digital tool
The due date calculator predicts the expected date of birth and the current week of pregnancy. You can start from the first day of your last period or from the date of conception, if you know it. The result includes the estimated date, the week and day, the trimester and how many days remain.
For the last period, Naegele's rule is used: the due date is 280 days (40 weeks) after the first day of the last period. If you start from the conception date, 266 days are used. Only a small share of babies are born exactly on the predicted date; a normal birth happens within a few weeks around it. The result is for information; the exact date is set by your gynaecologist, usually with an ultrasound.
How to use
- Enter the date of your last period or the conception date.
- See the predicted due date.
- See the current week and trimester.
Frequently asked questions
How accurate is the due date?
Only about 5% of babies are born exactly on the due date. Most are born within ±2 weeks of it.
How is the due date calculated?
By Naegele's rule, due date = first day of the last period + 280 days (40 weeks). If you know the conception date, 266 days are added.
What are the trimesters of pregnancy?
The first trimester runs to week 12, the second from week 13 to 26, and the third from week 27 until birth. The calculator shows which trimester you are in.
Can I give birth before or after the due date?
Yes, it is very common. The date is an estimate; most births happen a few days or weeks before or after it. The doctor may correct the date after an ultrasound.