Pregnancy Due Date Calculator
Calculate your estimated due date and see your pregnancy week-by-week timeline.
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Estimated Due Date
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Enter your date
How Due Dates Are Calculated
The most common method is Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation around day 14. If your cycle is longer or shorter, the calculation adjusts accordingly.
Due Date = LMP + 280 days (adjusted for cycle length)
Or: Due Date = Conception Date + 266 days
Or: Due Date = Conception Date + 266 days
Pregnancy Trimesters
| Trimester | Weeks | Key Milestones |
|---|---|---|
| First | 1–13 | Heartbeat, organs form |
| Second | 14–27 | Gender visible, movement felt |
| Third | 28–40+ | Rapid growth, lungs mature |
Disclaimer: This tool provides estimates for informational purposes only and is not medical advice. Consult your healthcare provider for prenatal care.
Frequently Asked Questions
How is my due date calculated?
The standard method (Naegele's rule) adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a 28-day cycle with ovulation on day 14.
How accurate is the due date?
Only about 5% of babies are born on their exact due date. Most arrive within two weeks before or after. The due date is an estimate, not a deadline.
Can I calculate my due date from conception date?
Yes. If you know your conception date, add 266 days (38 weeks). This is more accurate than LMP if you track ovulation.
What are the three trimesters?
First trimester: weeks 1–13. Second trimester: weeks 14–27. Third trimester: weeks 28–40+. Each has different milestones and symptoms.
When should I take a pregnancy test?
Take a home pregnancy test on or after the first day of your missed period (about 4 weeks pregnant). Blood tests can detect pregnancy 7–10 days after conception.