Pregnancy Due Date Calculator
Your estimated due date, how far along you are, and your current trimester.
How the due date is estimated
This uses Naegele's rule: due date = first day of your last menstrual period + 280 days (40 weeks), adjusted for your cycle length (each day over or under a 28-day cycle shifts ovulation and the due date by a day). Conception is estimated at 14 days before the end of your cycle.
How accurate is it?
Only about 4 or 5% of babies arrive on their due date; roughly 90% arrive within two weeks either side. A first-trimester ultrasound is more accurate than any date-based rule and will override this estimate. Your provider's dating is the one that counts. This calculator is informational, not medical advice.