Pregnancy Due Date Calculator: Find Your Estimated Delivery Date
When will your baby arrive? Your estimated due date (EDD) is one of the most important numbers in pregnancy. It guides every prenatal appointment, screening test, and birth plan decision you will make over the next nine months.
How the Due Date Is Calculated
This calculator uses Naegele's Rule — the standard obstetric formula used by obstetricians worldwide since the early 1800s. Despite its age, it remains the clinical standard because it is simple, reliable, and well-validated against birth outcome data.
Naegele's Rule: Add 280 days (40 weeks) to the first day of your last menstrual period (LMP).
For cycles longer or shorter than 28 days, the calculator adjusts: EDD = LMP + 280 days + (Cycle Length − 28) days
Worked Example
LMP: January 1. Cycle length: 30 days.
EDD = January 1 + 280 days + 2 days = October 10
Find your EDD instantly with our Pregnancy Due Date Calculator.
What the Result Tells You
| Information | What It Means |
|---|
| Estimated Due Date | Your target delivery date (±2 weeks is normal) |
| Weeks Pregnant Today | Current gestational age |
| Trimester | First (1–13 weeks), Second (14–26), Third (27–40) |
| Days Until Due Date | Countdown to expected delivery |
Important Facts About Due Dates
- Only 4% of babies are born on their exact due date. A range of 37–41 weeks is considered full term.
- Ultrasound is more accurate in early pregnancy. A 6–10 week scan provides the most precise gestational dating, especially with irregular cycles.
- First pregnancies tend to go slightly longer. Average first delivery is 41 weeks and 1 day.
- Multiple pregnancies often arrive earlier. Twins typically arrive around 36–37 weeks.
The Three Trimesters
First Trimester (Weeks 1–13): Major organ formation. Morning sickness common. Miscarriage risk highest. Prenatal vitamins with folic acid are most critical here.
Second Trimester (Weeks 14–26): Most women feel best in this phase. Baby movements felt (quickening). Anatomy scan typically at 18–20 weeks.
Third Trimester (Weeks 27–40): Rapid growth phase. Preparation for birth. Group B Strep test around 36 weeks. Hospital bag should be ready from week 36.
Practical Tips
Schedule your first prenatal appointment early. Ideally within 8 weeks of your LMP. Early appointments include blood tests, dating scans, and risk assessments.
Start prenatal vitamins immediately. Folic acid is most important in the first 12 weeks for neural tube development — even before you know you are pregnant.
Avoid alcohol completely. No safe level of alcohol consumption during pregnancy has been established.
Ask about your adjusted EDD at your 12-week scan. If your scan date differs by more than 7 days, your due date may be revised by your midwife or OB.
Final Thoughts
Your due date is an estimate, not a deadline. Births between 37–42 weeks are considered normal. Focus on prenatal care, nutrition, and regular check-ups — these matter far more than the exact date on the calendar.
Find your estimated due date with our free Pregnancy Due Date Calculator.
This calculator provides an estimate only. Consult your obstetrician or midwife for accurate gestational dating and personalised care.