Pregnancy Due Date Calculator
Find your estimated due date and track pregnancy week by week from your last period or conception date.
Our free pregnancy calculator estimates your due date (EDD) and tracks your gestational age week by week. Simply enter the first day of your last menstrual period (LMP) — the due date is calculated using Naegele's rule: LMP + 280 days (40 weeks). If you know your conception date, switch to conception mode and add 266 days (38 weeks) to get the same result.
The pregnancy due date calculator also shows your current trimester, the number of weeks and days elapsed, and key milestone dates throughout pregnancy. Whether you're tracking an early pregnancy or planning ahead, this free EDD calculator gives you instant results — no registration needed.
Frequently Asked Questions
How is the due date (EDD) calculated?
The calculator uses Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). In conception mode, 266 days (38 weeks) are added to the conception date — giving the same result, assuming conception occurred on day 14 of the cycle.
What is EDD (Estimated Due Date)?
EDD stands for Estimated Due Date — the date your baby is expected to be born. It is calculated at 40 weeks (280 days) from the last menstrual period. The EDD is an estimate: only about 5% of babies are born exactly on that day.
What is the difference between LMP mode and conception date mode?
The "Last Period" (LMP) mode is the standard medical method — doctors use it because the LMP date is easy to remember. The "Conception Date" mode is useful if you know the exact date, for example after IVF treatment or with ovulation tracking apps.
How accurate is the due date calculator?
Naegele's rule gives a reliable statistical estimate. Most births occur within 2 weeks before or after the EDD. A first-trimester ultrasound (weeks 8–12) provides the most accurate individual estimate and may adjust the calculated date.
What are the trimesters of pregnancy?
1st trimester (weeks 1–13): organ and neural tube formation, high miscarriage risk. 2nd trimester (weeks 14–26): rapid growth, baby starts moving, visible on ultrasound. 3rd trimester (weeks 27–40): final lung and brain development, preparation for birth.
What is gestational age?
Gestational age is the number of weeks and days since the first day of the last menstrual period. For example, "12 weeks 3 days" means 87 days have passed since LMP. Embryonic age (from conception) is typically 2 weeks less than gestational age.
My periods are irregular — can I still use this calculator?
Yes, but results will be less accurate. With irregular cycles, the assumed ovulation on day 14 may not apply. In this case, use the "Conception Date" mode if you know when conception occurred, or rely on a first-trimester ultrasound for a more precise due date.
Can I use my IVF transfer date to calculate the due date?
Yes. For IVF, the gestational age is calculated differently. For a Day 5 blastocyst transfer, add 261 days (37 weeks + 2 days) to the transfer date. For a Day 3 transfer, add 263 days. Many IVF clinics provide the adjusted EDD directly.
What if my baby is born before or after the due date?
Births between 37 and 42 weeks are considered full-term. Births before 37 weeks are preterm; after 42 weeks, post-term. If labour hasn't started by 41–42 weeks, doctors may recommend induction.
When should I see a doctor during pregnancy?
As soon as you suspect or confirm pregnancy — ideally before week 10. Early prenatal care allows fetal development monitoring, ultrasound to confirm the due date, screening tests, and early detection of any complications.
What is the difference between gestational age and embryonic age?
Gestational age is measured from the LMP and is the standard used in clinical practice. Embryonic (fetal) age is measured from conception and is approximately 2 weeks less. At 40 weeks gestational age, the embryo is about 38 weeks old.