Pregnancy Due Date Calculator
Estimate your baby's due date based on the first day of your last menstrual period or your conception date. See your current week, trimester, and a visual timeline of your pregnancy.
How to Use
Choose whether to calculate from your last menstrual period (LMP) or from your conception date. Enter the appropriate date and click Calculate Due Date. The calculator will show your estimated due date, how many weeks pregnant you are, which trimester you are in, and how many days remain until your due date.
Formula — Naegele's Rule
From LMP: Due Date = LMP + 280 days (40 weeks)
From Conception: Due Date = Conception Date + 266 days (38 weeks)
Naegele's rule is the standard method used by healthcare providers to estimate a due date. It assumes a 28-day menstrual cycle with ovulation occurring on day 14. The first trimester spans weeks 1–12, the second trimester weeks 13–26, and the third trimester weeks 27–40. Only about 5% of babies are born on their exact due date — most arrive within two weeks before or after.