Pregnancy Due Date Calculator
Estimate your pregnancy due date based on the first day of your last menstrual period (LMP). Uses Naegele's rule.
Select the date of your last period.
Naegele's Rule
Due Date = LMP + 280 days (40 weeks)
This method assumes a 28-day menstrual cycle and ovulation on day 14. The estimated due date is 280 days (40 weeks) from the first day of the last menstrual period.
Trimester Breakdown
| Trimester | Weeks |
|---|---|
| First | 1–12 |
| Second | 13–26 |
| Third | 27–40 |
Important Notes
- Only about 5% of babies are born on their exact due date.
- Normal delivery ranges from 37 to 42 weeks.
- An ultrasound in early pregnancy provides a more accurate estimate.
Disclaimer: This is an estimate. Please confirm your due date with your healthcare provider via ultrasound dating.
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Last updated: 2026-08-08