Pregnancy Due Date Calculator
Estimate your pregnancy due date, current pregnancy week, trimester, and days remaining using your last menstrual period date and cycle length.
Add your last menstrual period date to estimate your baby due date.
What Is a Pregnancy Due Date Calculator?
A Pregnancy Due Date Calculator estimates when your baby may be due based on the first day of your last menstrual period. It also estimates pregnancy week, trimester, days remaining, and an approximate conception window.
How Due Date Is Calculated
A common method is to add 280 days, or 40 weeks, to the first day of the last menstrual period. This calculator also adjusts slightly based on average cycle length.
| Input | Meaning |
|---|---|
| Last Menstrual Period | The first day of your last period. |
| Cycle Length | Your usual number of days between periods. |
| Estimated Due Date | Approximate date around 40 weeks from LMP, adjusted for cycle length. |
Pregnancy Weeks and Trimesters
| Trimester | Weeks | General Stage |
|---|---|---|
| First Trimester | Week 1–13 | Early pregnancy stage |
| Second Trimester | Week 14–27 | Middle pregnancy stage |
| Third Trimester | Week 28–40+ | Final pregnancy stage before birth |
Estimated Conception Date
Conception is often estimated around two weeks after the last menstrual period for a 28-day cycle. However, ovulation timing varies from person to person, so this is only an estimate.
Why Due Dates Can Change
- Cycle length may not be exactly 28 days
- Ovulation timing can vary
- Ultrasound dating may give a different estimate
- Baby growth and medical factors can affect planning
Due Date Calculator FAQ
Is this due date exact?
No. It is an estimate. Healthcare professionals may update the due date after ultrasound or clinical review.
What if I do not know my cycle length?
Use 28 days as a common default estimate.
Can I calculate my pregnancy week?
Yes. This calculator estimates your current pregnancy week based on the LMP date.
Does cycle length affect due date?
Yes. Longer cycles may slightly shift the estimate later, while shorter cycles may shift it earlier.