Calculate your pregnancy due date instantly. Enter your last menstrual period (LMP) or conception date and get your estimated due date, current week of pregnancy, and a trimester-by-trimester timeline.
How Is the Due Date Calculated?
The standard method uses Naegele’s Rule: add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle. For longer or shorter cycles, the due date is adjusted accordingly. Only about 5% of babies are born on their exact due date, but 80% arrive within two weeks of it.
Frequently Asked Questions
How accurate is the due date calculator?
Due date calculators using LMP are accurate to within 1-2 weeks for most pregnancies. The most accurate method is an early ultrasound (before 12 weeks), which measures the baby’s size to confirm or adjust the EDD.
What are the three trimesters?
The first trimester covers weeks 1-13, the second covers weeks 14-27, and the third covers weeks 28-40. Each trimester brings distinct developmental milestones and physical changes.
What if my cycle is not 28 days?
If your cycle is longer than 28 days, ovulation happens later, pushing the due date back. If shorter, the due date moves forward. Our calculator adjusts for your cycle length automatically.
What is a full-term pregnancy?
A full-term pregnancy is 39-40 weeks. Babies born at 37-38 weeks are “early term,” at 41 weeks are “late term,” and at 42+ weeks are “post-term.” Most doctors recommend induction by 42 weeks.
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