Pregnancy Due Date Calculator — Free Online Health Calculator | No Signup
| Distance | Estimated Finish Time |
|---|---|
| 5K | --:--:-- |
| 10K | --:--:-- |
| Half Marathon (21.1K) | --:--:-- |
| Marathon (42.2K) | --:--:-- |
Our Pregnancy Due Date Calculator estimates your baby's arrival date using Naegele's Rule — the standard method used by healthcare providers worldwide. Enter your last menstrual period date and get an instant estimated due date, current pregnancy week, and key milestones.
How to Use the Pregnancy Due Date Calculator
- Enter your LMP: Select the first day of your last menstrual period.
- Adjust cycle length: Default is 28 days — change if your cycle is shorter or longer.
- Read your results: Estimated due date, current week, trimester, and days remaining appear instantly.
How We Calculate Your Due Date
We use Naegele's Rule: EDD = LMP + 280 days (40 weeks). If your cycle differs from 28 days, we adjust accordingly: EDD = LMP + 280 + (cycle length - 28) days.
| Trimester | Weeks | Key Developments |
|---|---|---|
| First | 1-12 | Organ formation, heartbeat begins at week 6 |
| Second | 13-26 | Movement felt, gender visible, rapid growth |
| Third | 27-40 | Weight gain, lung maturity, birth preparation |
Frequently Asked Questions
How accurate is the estimated due date?
Only about 5% of babies are born on their exact due date. The EDD is an estimate based on a 40-week average pregnancy. Most babies arrive within 2 weeks before or after the due date. An ultrasound in the first trimester provides the most accurate dating.
What if I don't know my last period date?
If you know your conception date, add 266 days (38 weeks) to get an estimated due date. Your doctor can also estimate your due date using an early ultrasound measurement of the embryo.
What does "full term" mean?
Full term is defined as 39-40 weeks of pregnancy. Babies born at 37-38 weeks are "early term," while those born at 41 weeks are "late term." Most doctors consider 40 weeks the target for a healthy, full-term pregnancy.
Related Tools
Calorie Calculator
Calculate daily calorie needs — including during pregnancy.
Water Intake Calculator
Daily water intake recommendation by weight and activity.
Age Calculator
Calculate exact age in years, months, and days.
Date Difference Calculator
Calculate days between any two dates.
This calculator provides estimates for informational purposes only. Always consult your healthcare provider for accurate pregnancy dating and medical advice. Sources: American College of Obstetricians and Gynecologists (ACOG).