Pregnancy Due Date
Calculator
Calculate your estimated due date from your last period or conception date. Includes trimester timeline and key milestones.
2nd Trimester
3rd Trimester
⚕ Estimated due date based on Naegele's rule (280 days from LMP). Only about 5% of babies are born on their exact due date. Always confirm with your healthcare provider.
Frequently Asked Questions
How is the due date calculated?
Most due dates are calculated using Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, the actual conception date may vary. Your doctor may adjust the due date after an ultrasound, which is more accurate in early pregnancy.
What if I don't know my last period date?
You can use your estimated conception date instead — our calculator adds 266 days (38 weeks) from conception to estimate the due date, since conception typically occurs about 14 days after the start of your LMP. An early ultrasound (before 14 weeks) can also establish a due date by measuring the fetus.
How accurate is an estimated due date?
The estimated due date (EDD) is just that — an estimate. Only about 5% of babies are born on their exact due date. Most babies arrive within 2 weeks before or after. Full-term pregnancy is considered 39–40 weeks, while 37–42 weeks is the normal range. Your doctor will monitor for post-term pregnancy if you go past 42 weeks.
What are the three trimesters?
The first trimester runs from week 1 to week 13 — the most critical period for organ development. The second trimester is weeks 14–27, when most women feel the best and the baby grows rapidly. The third trimester is weeks 28–40, when the baby gains most of its weight and prepares for birth. Each trimester brings distinct developmental milestones and physical changes.
How is IVF due date different?
For IVF with a 5-day blastocyst transfer, the due date is calculated as 261 days (37 weeks + 2 days) from the transfer date. For a 3-day embryo transfer, add 263 days. This is because the embryo's age is already known precisely — there's no need to estimate conception timing. Our calculator uses the 5-day blastocyst standard.
When should I announce my pregnancy?
Many people wait until after the first trimester (around week 12–13) to announce, as the risk of miscarriage drops significantly after week 10 (from ~10% to under 1%). The first trimester is also when genetic screening tests like NIPT and nuchal translucency ultrasounds are done. That said, when to share is entirely personal — there's no medical rule.