Due Date Calculator
Free due date calculator: enter your last period or conception date to get the estimated due date, gestational age, trimester and key check-up dates.
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How to Use
- Choose a method
Use the first tab if you know the first day of your last period, or switch to the second tab if you know the conception date.
- Enter date and cycle
Pick the date and adjust for your actual cycle length; anything from 21 to 35 days is common.
- Read the schedule
The panel shows the due date, gestational age, days pregnant and days remaining, with suggested dates for each check-up milestone below.
FAQ
How is the due date calculated?
Naegele's rule: due date = first day of the last period + 280 days (40 weeks). If your cycle is not 28 days, adjust by the difference — each extra cycle day pushes the due date one day later.
Will I deliver on the due date?
Unlikely. Only about 5% of babies arrive on the exact day, and delivery between 37 and 42 weeks is normal. The due date is a statistical midpoint used to schedule check-ups and assess growth.
When does gestational age start?
Medically it starts on the first day of your last period, not at conception, so gestational age is about two weeks ahead of the actual pregnancy. That is why the first two of the 40 weeks happen before conception.
What if I go past the due date?
Beyond 41 weeks is post-term, requiring closer fetal monitoring and a discussion about induction. The tool shows how many days past the due date you are.