Due Date Calculator
Estimate your baby's due date from your last period or conception date.
Starting point
Pick a date.
Naegele's rule
The classic estimate adds 280 days (40 weeks) to the last period's first day, assuming a 28-day cycle with ovulation at day 14. Counting from conception uses 266 days; IVF transfers are the most precise, dated from the embryo's exact age.
A window, not an appointment
Term spans 37–42 weeks: about 60% of babies arrive within a week of the due date, and first pregnancies tend to run a few days late. Treat the date as the center of a month-wide window.
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