Calculate your estimated due date and pregnancy timeline
The calculator uses two standard methods: Naegele's Rule adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). Conception Date method adds 266 days (38 weeks) from the estimated conception date. Both methods assume a standard 28-day cycle with ovulation on day 14.
Knowing your estimated due date helps you plan prenatal care, prepare for maternity leave, and track your baby's developmental milestones. It provides a timeline for important tests and screenings throughout your pregnancy journey.
Pregnancy is measured from the first day of your last period, not conception. This adds about 2 weeks to the actual age of the fetus. First trimester: weeks 1-12. Second trimester: weeks 13-27. Third trimester: weeks 28-40. Full term is 39-40 weeks.
If your cycles are irregular or you don't remember your LMP, your healthcare provider may use ultrasound measurements in the first trimester for more accurate dating. Keep a record of your periods before trying to conceive for the most precise estimate.
Due date is typically calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP), or 266 days (38 weeks) from conception date.
Only about 5% of babies are born on their exact due date. Most babies arrive within 2 weeks before or after the estimated due date. It's best used as a general guideline.
Use LMP if you know the first day of your last period. Use conception date only if you know the exact date of conception, which provides a more accurate estimate.