Estimate your baby's due date from the first day of your last period, or from a known conception date. Instant result — no sign-up needed.
Most due dates are estimated using Naegele's Rule: adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a average 28-day cycle with ovulation around day 14.
If you know your conception date instead — for example, from IVF or ovulation tracking — your due date is estimated as 266 days (38 weeks) from that date, since conception typically occurs about two weeks after the start of your last period.
Only about 1 in 20 babies are born on their exact estimated due date. Most babies arrive within a window of two weeks before to one week after this date. Your due date is a helpful planning estimate, not a prediction — your doctor may adjust it based on an early ultrasound, which is often more accurate than LMP-based calculations, especially if your cycle is irregular.
This calculator is for general planning only. Always confirm your due date and any pregnancy concerns with your OB-GYN or midwife, who can adjust the estimate using ultrasound measurements and your individual health history.
BabyQuil turns this due date into a week-by-week tracker — symptoms, appointments, weight, and contractions, all in one place.
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