Pregnancy Due Date Calculator

The most common method uses Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle; the calculator adjusts for different cycle lengths. Conception-based calculation adds 266 days (38 weeks) from the estimated conception date.

The due date is an estimate. Only about 5% of babies are born on their exact due date. Most babies are born within 2 weeks before or after the due date. An early ultrasound (before 12 weeks) is considered the most accurate method for dating a pregnancy.

Use the LMP method if you know the first day of your last period. Use the conception method if you tracked ovulation or know when you conceived. Use the IVF method if you had an embryo transfer, selecting day 3 or day 5 (blastocyst). Use the ultrasound method if your provider confirmed gestational age via scan.

Gestational age is the age of the pregnancy measured from the first day of the last menstrual period. It is typically 2 weeks ahead of fetal age (which is counted from conception). For example, at 8 weeks gestational age, the embryo is approximately 6 weeks old.

For a day 5 blastocyst transfer, the due date is calculated by adding 261 days to the transfer date. For a day 3 transfer, 263 days are added. This accounts for the embryo's age at the time of transfer, mapping back to an equivalent LMP date for standard pregnancy tracking.

Yes! The LMP method assumes a standard 28-day cycle with ovulation on day 14. If your cycle is longer or shorter, the calculator adjusts the due date accordingly. For example, a 35-day cycle pushes the due date 7 days later than a standard calculation.

The first trimester spans weeks 1–12, covering major organ formation. The second trimester covers weeks 13–26, when movement becomes noticeable and the anatomy scan is performed. The third trimester is weeks 27–40, focused on growth and preparation for birth.

A full-term pregnancy is defined as 39 to 40 weeks of gestation. Babies born between 37 and 39 weeks are considered 'early term,' while those born between 39 and 41 weeks are 'full term.' Births after 42 weeks are considered post-term.

The anatomy (or anomaly) scan is typically performed around 18–22 weeks of pregnancy, often scheduled at 20 weeks. It checks the development of the baby's organs and can usually confirm the sex of the baby if desired.

Fetal viability refers to the point at which a baby could potentially survive outside the womb with medical support, generally considered to be around 24 weeks of gestation. Survival rates increase significantly with each additional week after this point.

This calculator is a planning and estimation tool — it does not confirm pregnancy. If you think you may be pregnant, use a home pregnancy test and consult a healthcare provider for confirmation, accurate dating, and prenatal care guidance.

No. This tool is for informational and planning purposes only. For accurate pregnancy dating, medical monitoring, and personalized advice, always consult a qualified healthcare provider or obstetrician.