Calculate your due date, current week of pregnancy, trimester, and see a complete milestone timeline.
Pregnancy Summary
About the Pregnancy Calculator
This calculator estimates your pregnancy due date and current gestational age using your last menstrual period (LMP) and Naegele's rule, the standard obstetric method used by healthcare providers worldwide.
How to Use
Enter the first day of your last menstrual period (LMP).
Optionally adjust the cycle length (default 28 days). For cycles other than 28 days, the due date is adjusted accordingly.
Click Calculate.
View your due date, current week, trimester, and milestone timeline.
How It Works
Naegele's Rule: Due Date = LMP + 280 days (40 weeks)
For non-28-day cycles: Due Date = LMP + 280 + (cycle length − 28) days
Gestational age is counted from the LMP, even though conception typically occurs around day 14.
Trimesters
First trimester: Weeks 1–12 · Second trimester: Weeks 13–26 · Third trimester: Weeks 27–40
Frequently Asked Questions
Only about 5% of babies are born exactly on their due date. The due date represents the midpoint of a range — 80% of babies are born between weeks 38 and 42. Ultrasound dating (especially in the first trimester) may be more accurate.
Gestational age is counted from the LMP and is used by doctors. Fetal age (embryonic age) is counted from conception — typically 2 weeks less than gestational age. The due date at 40 weeks gestational age = 38 weeks fetal age.
Enter your average cycle length. The calculator adjusts the due date: longer cycles shift the due date later, shorter cycles shift it earlier. Each day difference in cycle length equals one day shift in due date.
No. Always confirm your due date with your healthcare provider, who may use ultrasound measurements for more accurate dating, especially in early pregnancy.