Pregnancy Week Tracker
Enter your due date or last menstrual period (LMP) to see your current pregnancy week, trimester, baby size comparison, and how far along you are.
Frequently Asked Questions
How is gestational age calculated?
Gestational age is measured in weeks and days from the first day of your last menstrual period (LMP). A full-term pregnancy is 40 weeks (280 days). If you enter your estimated due date (EDD), we subtract 280 days to derive your LMP and then count forward to today.
What is the difference between gestational age and fetal age?
Gestational age counts from your LMP, which is about 2 weeks before ovulation. Fetal age (embryonic age) counts from fertilization. Most medical dates—including those on ultrasounds and prenatal visits—use gestational age.
When do the trimesters start and end?
The first trimester spans weeks 1–12. The second trimester covers weeks 13–27. The third trimester runs from week 28 until birth, typically around week 40. These boundaries may vary slightly by source.
Why does my tracker show a different week than my doctor?
Your doctor may adjust your estimated due date based on first-trimester ultrasound measurements, which can be more accurate than LMP dating. Small differences of a few days are common. Always follow your healthcare provider's dating.
Can I track my pregnancy past 40 weeks?
Yes. Some pregnancies last up to 42 weeks. This tracker supports gestational ages from conception through 42 weeks. Pregnancies beyond 42 weeks are considered post-term and require medical monitoring.
Clinical Source
Gestational age calculations on this page follow standards published by the World Health Organization (WHO) and the American College of Obstetricians and Gynecologists (ACOG). Trimester boundaries and fetal size data are based on WHO fetal growth charts and peer-reviewed obstetrics references. This tool is for informational purposes only and does not replace professional medical advice.