Pregnancy Due Date Calculator
Calculate your estimated due date from your last period, conception date, or IVF transfer.
Frequently Asked Questions
How is the due date calculated from last menstrual period (LMP)?
Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a regular 28-day cycle with ovulation on day 14. For cycles longer or shorter than 28 days, conception (and therefore the due date) shifts by the same number of days. Your provider may adjust the date after a first-trimester ultrasound, which is more accurate.
How many weeks pregnant am I?
Pregnancy is counted from the first day of your last period, not from conception. So at the moment of conception you're technically "2 weeks pregnant." At your first missed period (4 weeks LMP), you're 4 weeks pregnant. Enter your LMP date in the calculator to get your exact gestational age in weeks and days.
What is the difference between Day 3 and Day 5 IVF embryo transfer?
A Day 3 transfer (cleavage-stage embryo) adds 263 days to the transfer date to get the EDD. A Day 5 transfer (blastocyst) adds 261 days. The 2-day difference reflects the extra development time in the lab. Day 5 blastocysts have higher implantation rates and are more commonly used in modern IVF cycles.
When does each trimester start and end?
Standard trimester divisions: 1st trimester = weeks 1–12 (organogenesis, highest miscarriage risk). 2nd trimester = weeks 13–28 (rapid growth, typically the most comfortable period). 3rd trimester = weeks 29–40 (final development, preparation for birth). Full term is 39–40 weeks; 37–38 weeks is early term; 41+ weeks is late term.
How likely is it to give birth exactly on the due date?
Only about 4–5% of babies are born on their exact due date. About 80% are born within 2 weeks of the EDD (weeks 38–42). The EDD is a statistical midpoint of normal delivery dates — not a deadline. Births before 37 weeks are preterm; after 42 weeks is post-term (at which point induction is typically recommended).