Pregnancy Due Date Calculator from Last Period
Add 280 days (40 weeks) to the first day of your last menstrual period to get your due date. If your LMP was January 1, your due date is October 8. Only about 5% of babies arrive on the exact due date - most arrive within 2 weeks of it.
Due Date
Thu, November 19, 2026
224 days remaining
Currently Pregnant
8w 0d
Trimester
First Trimester
Key Milestones
Week 8 — Heartbeat detectable
Thu, April 9, 2026
Week 12 — End of first trimester
Thu, May 7, 2026
Week 20 — Anatomy / anomaly scan
Thu, July 2, 2026
Week 28 — Viability milestone
Thu, August 27, 2026
Week 36 — Full term approaching
Thu, October 22, 2026
Week 40 — Due date
Thu, November 19, 2026
Naegele's rule: due date = LMP + 280 days (40 weeks). Trimesters: T1 = weeks 1-13, T2 = weeks 14-27, T3 = weeks 28-40. Always confirm with your healthcare provider.
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Common questions about Pregnancy Due Date Calculator from Last Period
How accurate is the LMP method for calculating due date?
The LMP method assumes a 28-day cycle and ovulation on day 14. It is accurate within 1-2 weeks for most women. If your cycle is longer (e.g., 35 days), your due date shifts forward by a week. An early ultrasound at 8-12 weeks is the most accurate way to confirm gestational age.
What week does each trimester start?
First trimester: weeks 1-13. Second trimester: weeks 14-27. Third trimester: weeks 28-40. Most women discover pregnancy around weeks 4-6, which is already mid-first trimester by LMP dating.
Can I calculate due date from conception date instead of LMP?
Yes. If you know your conception date, add 266 days (38 weeks) to it. Ovulation typically happens 14 days after LMP, so conception date plus 266 days equals LMP plus 280 days - they give the same result when timed correctly.