Pregnancy Due Date Calculator

What is a Pregnancy Due Date?

The estimated due date (EDD) is the projected date of delivery calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This method, known as Naegele's Rule, has been the medical standard since the 19th century. The 40-week pregnancy is divided into three trimesters: the first trimester (weeks 1–12) covering early development, the second trimester (weeks 13–26) of rapid growth, and the third trimester (weeks 27–40) of final development and birth preparation. Only about 5% of babies are born on their exact due date.

How to Use This Calculator

Enter the date of the first day of your last menstrual period in YYYY-MM-DD format (for example, 2025-03-15). Click Calculate to see your estimated due date, current week of pregnancy, trimester you are in, days remaining until your due date, and total days pregnant so far. The calculator also provides stage-appropriate health guidance based on your current week.

💡 Pro Tips

• ✓Ultrasound dating in the first trimester is more accurate than LMP dating — use ultrasound dates if available.
• ✓The due date is an estimate — most healthy pregnancies deliver anywhere between 38 and 42 weeks.
• ✓Start prenatal vitamins with folic acid as soon as pregnancy is confirmed — ideally before conception.
• ✓Attend all scheduled prenatal appointments — they are timed to catch potential issues at the right stages.
• ✓Track fetal movements from around week 28 — contact your doctor if you notice reduced movement.

Who Uses This Calculator?

Pregnant women tracking their pregnancy week and trimester. Partners and family planning for the expected arrival. Obstetricians and midwives verifying gestational age. HR professionals planning maternity leave timing. Parents planning childcare and nursery preparation around the due date.

Frequently Asked Questions