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Due Date Calculator
Calculate your estimated due date from your last menstrual period, conception date, IVF transfer, or ultrasound. See trimester milestones and a week-by-week pregnancy countdown.
days
Quick Facts
Average pregnancy40 weeks (280 days)
Full term range39-40 weeks
Babies born on due date~5%
Trimesters3 (13-14 weeks each)
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How to Use This Calculator
- Select your calculation method: Last Menstrual Period, Conception Date, IVF Transfer, or Ultrasound.
- Enter the relevant date for your chosen method.
- For IVF, select whether a Day 3 or Day 5 embryo was transferred.
- Click Calculate to see your estimated due date, current week, and trimester timeline.
The Formula
LMP method: Due Date = LMP + 280 days (Naegele's rule). Conception: Due Date = Conception + 266 days. IVF Day 5: Due Date = Transfer + 261 days. IVF Day 3: Due Date = Transfer + 263 days.Frequently Asked Questions
Only about 5% of babies are born on their exact due date. Most are born within 2 weeks before or after. The LMP method assumes a 28-day cycle with ovulation on day 14, which varies between individuals.